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When finite defects force one-sided ellipticity

Written and dedicated to the public domain by Codex, September 2026 (CC0).

A closed range with only finitely many null solutions forces a pseudodifferential symbol to be injective at high frequency. A range with only finitely many missing targets forces the separate surjective condition. The two need not coincide for a rectangular system. This lesson proves both directions, then carries every source and target weight through a mixed-order system. It ends with an example showing exactly why an adapted graph domain changes the conclusion.

The required entry results are Finite defects under perturbation, From symbol estimates to operators on every Sobolev scale, and Symbols, finite defects, and the index on a closed manifold. Their compactness, complete symbol composition, and order-changing maps are recalled at the points where they enter. We use D=−i∂D=-i\partial, retain every matrix factor in its source-to-target order, and never identify distinct bundle fibers without the stated Hermitian metric.

1. Objects and the four one-sided assertions

Let XX be a compact smooth manifold without boundary. Let E,FE,F be finite-rank complex Hermitian bundles, with their half-density factors retained in the Sobolev spaces. Fix m,s∈ℝm,s\in\mathbb R and P∈Ψm(X;E⊗ΩX1/2,F⊗ΩX1/2),Ps:Hs(X;E⊗ΩX1/2)→Hs−m(X;F⊗ΩX1/2).(OM1) P\in\Psi^m(X;E\otimes\Omega_X^{1/2},F\otimes\Omega_X^{1/2}), \qquad P_s:H^s(X;E\otimes\Omega_X^{1/2}) \longrightarrow H^{s-m}(X;F\otimes\Omega_X^{1/2}). \tag{OM1} Here Ψm\Psi^m has the S1,0mS^m_{1,0} full-symbol bounds in local bundle frames, and p∈Sm/Sm−1p\in S^m/S^{m-1} is its original principal class. A representative pp is used when writing a pointwise high-frequency inequality. Changing representatives changes it by Sm−1S^{m-1}, so the inequalities below are independent of that choice after increasing the lower frequency cutoff. The positive function ⟨ξ⟩\langle\xi\rangle is defined by one fixed Riemannian cotangent metric; the original pp, its bundle maps and all orders remain explicit.

The left condition is ∥p(x,ξ)w∥F≥c⟨ξ⟩m∥w∥E(|ξ|≥R,w∈Ex).(OM2) \|p(x,\xi)w\|_F\ge c\langle\xi\rangle^m\|w\|_E \quad (|\xi|\ge R,\ w\in E_x). \tag{OM2} The right condition is the corresponding lower bound for the actual Hermitian adjoint p(x,ξ)*:Fx→Exp(x,\xi)^*:F_x\to E_x: ∥p(x,ξ)*v∥E≥c′⟨ξ⟩m∥v∥F(|ξ|≥R′,v∈Fx).(OM3) \|p(x,\xi)^*v\|_E\ge c'\langle\xi\rangle^m\|v\|_F \quad (|\xi|\ge R',\ v\in F_x). \tag{OM3} These conditions allow unequal ranks. The left one says injectivity with a uniform high-frequency bound, and the right one says surjectivity with a uniform high-frequency bound. Neither implies the other for a rectangular bundle map.

2. Finite kernel and closed range give a compact-error estimate

Assume PsP_s has finite-dimensional kernel NN and closed range. The restriction to the orthogonal complement N⟂⊂Hs(E)N^\perp\subset H^s(E) is a bounded bijection onto ran⁡Ps\operatorname{ran}P_s. Both are Hilbert spaces, so the bounded inverse theorem gives ∥u∥Hs≤C(∥Psu∥Hs−m+∥ΠNu∥Hs).(OM4) \|u\|_{H^s} \le C\bigl(\|P_su\|_{H^{s-m}}+\|\Pi_Nu\|_{H^s}\bigr). \tag{OM4} The projection ΠN\Pi_N is finite rank and compact; no smoothness of NN has been assumed.

The same hypotheses give the lower-order estimate required in the original Sobolev spaces: ∥u∥Hs≤Cs(∥Psu∥Hs−m+∥u∥Hs−1).(OM5) \|u\|_{H^s} \le C_s\bigl(\|P_su\|_{H^{s-m}}+\|u\|_{H^{s-1}}\bigr). \tag{OM5} If this failed, choose uju_j with ∥uj∥Hs=1\|u_j\|_{H^s}=1 and both terms on the right tending to zero. Equation (OM4) shows dist⁡Hs(uj,N)→0\operatorname{dist}_{H^s}(u_j,N)\to0. Choose nj∈Nn_j\in N with ∥uj−nj∥Hs→0\|u_j-n_j\|_{H^s}\to0. The continuous inclusion Hs↪Hs−1H^s\hookrightarrow H^{s-1} gives ∥nj∥Hs−1→0\|n_j\|_{H^{s-1}}\to0. Its restriction to the finite-dimensional NN is injective, so its Hs−1H^{s-1} and HsH^s norms on NN are equivalent. Thus ∥nj∥Hs→0\|n_j\|_{H^s}\to0, contradicting ∥uj∥Hs=1\|u_j\|_{H^s}=1. This argument does not silently make the unknown kernel smooth.

3. A local wave packet tests the complete original principal map

We record the quantitative packet fact used to derive (OM2). Let A∈Ψ0(X;E,F)A\in\Psi^0(X;E,F), with complete local symbol a(x,η)a(x,\eta), and choose a smaller chart whose closure lies in one bundle trivialization. Let λ=|ξλ|→∞\lambda=|\xi_\lambda|\to\infty, with xλx_\lambda in that smaller chart, and let wλw_\lambda be a unit vector in its local input frame. Choose χ∈Cc∞(ℝn)\chi\in C_c^\infty(\mathbb R^n) with ∥χ∥2=1\|\chi\|_2=1, and set vλ(x)=λn/4χ(λ1/2(x−xλ))ei⟨x−xλ,ξλ⟩wλ.(OM6) v_\lambda(x) =\lambda^{n/4}\chi\!\left(\lambda^{1/2}(x-x_\lambda)\right) e^{\,i\langle x-x_\lambda,\xi_\lambda\rangle}w_\lambda . \tag{OM6} The coefficient in (OM6) is written in the coordinate half-density frame |dx|1/2|dx|^{1/2}, using the stated input and output bundle frames. The unit condition means wλ†HE(xλ)wλ=1w_\lambda^\dagger H_E(x_\lambda)w_\lambda=1 in the original input metric at the center. The norm of the constant output matrix in (OM7) is taken in the specified output frame. The complete calculation below retains the fixed cotangent metric and its chart comparison constants; it includes the frequency derivatives needed for the operator estimate, not only the base derivatives.

The half-density and frame metrics vary smoothly on the shrinking support, so ∥vλ∥L2=1+O(λ−1/2),vλ⇀0 in L2,∥Avλ−a(xλ,ξλ)vλ∥L2=O(λ−1/2).(OM7) \|v_\lambda\|_{L^2}=1+O(\lambda^{-1/2}),\qquad v_\lambda\rightharpoonup0\text{ in }L^2,\qquad \|Av_\lambda-a(x_\lambda,\xi_\lambda)v_\lambda\|_{L^2} =O(\lambda^{-1/2}). \tag{OM7} The weak limit follows by Cauchy–Schwarz on a shrinking ball for each fixed L2L^2 test, first for bounded smooth tests and then by density.

For completeness, the last bound has two exact parts. On the support of vλv_\lambda, the mean-value formula and the uniform xx-derivatives of aa give ∥(a(x,ξλ)−a(xλ,ξλ))vλ∥2=O(λ−1/2)\|(a(x,\xi_\lambda)-a(x_\lambda,\xi_\lambda))v_\lambda\|_2 =O(\lambda^{-1/2}). The Fourier transform of the packet is centered at ξλ\xi_\lambda, with width λ1/2\lambda^{1/2}. Cut it to |η−ξλ|≤λ/2|\eta-\xi_\lambda|\le\lambda/2; the complementary Schwartz tail is O(λ−N)O(\lambda^{-N}) in every fixed Sobolev norm, for every NN. On the cut region the exact integral identity a(x,η)−a(x,ξλ)=∑r=1n(ηr−ξλ,r)∫01∂ηra(x,ξλ+θ(η−ξλ))dθ(OM8) a(x,\eta)-a(x,\xi_\lambda) =\sum_{r=1}^n(\eta_r-\xi_{\lambda,r}) \int_0^1\partial_{\eta_r}a (x,\xi_\lambda+\theta(\eta-\xi_\lambda))\,d\theta \tag{OM8} has coefficient symbols with every fixed xx-derivative bounded by Cλ−1C\lambda^{-1}. The finite-derivative L2L^2 symbol estimate from the linked symbol-calculus lesson, applied after the frequency cutoff, and ∥(D−ξλ)vλ∥2=O(λ1/2)\|(D-\xi_\lambda)v_\lambda\|_2=O(\lambda^{1/2}) give O(λ−1/2)O(\lambda^{-1/2}). Operators cut off away from the coordinate diagonal have smooth kernels; repeated integration by parts in the packet’s oscillation bounds their output by O(λ−N)O(\lambda^{-N}) for each NN. This proves (OM7), uniformly in the selected chart. A finite chart cover provides uniformity on XX.

The complete coordinate packet proof

The operator bound used here is the full finite-derivative symbol estimate, (E23), proved there in (E24)–(E27) and (EC12)–(EC14). Its derivative count can be taken as Ln=4N0L_n=4N_0, with an integer N0>n/2N_0>n/2. The Fourier conventions are (E10), and the exact kernel reconstruction is (E12).

1. Exact objects, metrics, density and local realization

Let XX be the original compact smooth manifold without boundary, and let E,FE,F be the original complex Hermitian bundles. Keep their half-density factors. Let A∈Ψ1,00(X;E⊗ΩX1/2,F⊗ΩX1/2).(PW1) A\in\Psi^0_{1,0} (X;E\otimes\Omega_X^{1/2},F\otimes\Omega_X^{1/2}). \tag{PW1} We give the proof on a component of dimension n≥1n\geq1. A zero-dimensional component has no covectors tending to infinity and consequently contributes no packet sequence to the necessity argument.

Choose one coordinate chart x=(x1,…,xn)x=(x_1,\ldots,x_n), input and output bundle frames, and nested relatively compact open subsets K⊂U0,U0¯⊂U1,U1¯⊂U2,U2¯⊂U,(PW2) K\subset U_0,\qquad \overline {U_0}\subset U_1,\qquad \overline {U_1}\subset U_2,\qquad \overline {U_2}\subset U , \tag{PW2} where KK is compact and every packet center xλx_\lambda belongs to KK. Choose fixed smooth cutoffs ψ,ζ\psi,\zeta, with ψ=1\psi=1 near U0¯\overline {U_0}, supp⁡ψ⊂U1\operatorname{supp}\psi\subset U_1, ζ=1\zeta=1 near U1¯\overline {U_1}, and supp⁡ζ⊂U2\operatorname{supp}\zeta\subset U_2. Use the coordinate half-density frame |dx|1/2|dx|^{1/2}. Write HE(x),HF(x)H_E(x),H_F(x) for the positive Hermitian metric matrices in the two specified frames. Thus, with the Hermitian pairing linear in its first variable, hE(u,v)=v†HE(x)u,∥u(x)|dx|1/2∥L2(E)2=∫u(x)†HE(x)u(x)dx.(PW3) h_E(u,v)=v^\dagger H_E(x)u,\qquad \|u(x)|dx|^{1/2}\|_{L^2(E)}^2 =\int u(x)^\dagger H_E(x)u(x)\,dx . \tag{PW3} There is no missing density multiplier in PW3: the square of the chosen half-density is exactly |dx||dx|. Under another coordinate system y=Φ(x)y=\Phi(x), the coefficient transforms with |det⁡DΦ−1(y)|1/2|\det D\Phi^{-1}(y)|^{1/2}; squaring that factor and changing variables preserves precisely PW3. Bundle frame changes transform the matrices and coefficients together, preserving the same integral.

On the compact coordinate region let 0<hE−≤λmin(HE(x)),0<hF−≤λmin(HF(x)),λmax(HE(x))≤hE+,λmax(HF(x))≤hF+.(PW4) 0<h_E^-\leq\lambda_{\min}(H_E(x)),\qquad 0<h_F^-\leq\lambda_{\min}(H_F(x)),\qquad \lambda_{\max}(H_E(x))\leq h_E^+,\quad \lambda_{\max}(H_F(x))\leq h_F^+ . \tag{PW4} All metric derivatives used below have finite suprema there. Write |η|c|\eta|_{\rm c} for the Euclidean coordinate covector norm and keep |η|g,x|\eta|_{g,x} for the fixed Riemannian cotangent norm already chosen in OM1. There are fixed constants 0<κ−≤κ+,κ−|η|c≤|η|g,x≤κ+|η|c.(PW5) 0<\kappa_-\leq\kappa_+,\qquad \kappa_-|\eta|_{\rm c}\leq|\eta|_{g,x} \leq\kappa_+|\eta|_{\rm c}. \tag{PW5} For example their squares can be taken as the minimum and maximum of the eigenvalues of the coordinate cotangent metric matrix on the compact region. These are exact inequalities between the two original norms.

Let a(x,η)a(x,\eta) be a complete local left symbol for AA, with all the original S1,00S^0_{1,0} bounds ∥∂xα∂ηβa(x,η)∥≤Mα,β⟨η⟩c−|β|,⟨η⟩c=(1+|η|c2)1/2.(PW6) \|\partial_x^\alpha\partial_\eta^\beta a(x,\eta)\| \leq M_{\alpha,\beta}\langle\eta\rangle_{\rm c}^{-|\beta|}, \qquad \langle\eta\rangle_{\rm c}=(1+|\eta|_{\rm c}^2)^{1/2}. \tag{PW6} Its source and target coordinate dimensions are kept distinct. The local realization of the pseudodifferential class means ζAψ=ζOp⁡(a)ψ+R\zeta A\psi=\zeta\operatorname{Op}(a)\psi+R, where RR has a smooth localized kernel. Here left quantization is exactly û(η)=∫e−ix⋅ηu(x)dx,Op⁡(a)u(x)=(2π)−n∫eix⋅ηa(x,η)û(η)dη,Dr=−i∂xr.(PW7) \widehat u(\eta)=\int e^{-ix\cdot\eta}u(x)\,dx,\qquad \operatorname{Op}(a)u(x)=(2\pi)^{-n} \int e^{ix\cdot\eta}a(x,\eta)\widehat u(\eta)\,d\eta , \qquad D_r=-i\partial_{x_r}. \tag{PW7} These are E10’s conventions. Put ã=ζa\widetilde a=\zeta a, extended by zero outside the chart. It is a global Euclidean S1,00S^0_{1,0} symbol. The exact derivative formula is ∂xα∂ηβã=∑ν≤α(αν)(∂xνζ)(∂xα−ν∂ηβa).(PW8) \partial_x^\alpha\partial_\eta^\beta\widetilde a =\sum_{\nu\leq\alpha}{\alpha\choose\nu} (\partial_x^\nu\zeta) (\partial_x^{\alpha-\nu}\partial_\eta^\beta a). \tag{PW8} This retains every output-cutoff contribution. In particular PW6 holds for ã\widetilde a, with new fixed constants M̃α,β\widetilde M_{\alpha,\beta} bounded by the finite sum in PW8.

2. The packet and its exact norm and Fourier transform

Keep the original packet profile χ∈Cc∞(ℝn)\chi\in C_c^\infty(\mathbb R^n) with ∫|χ(z)|2dz=1\int|\chi(z)|^2\,dz=1, and put Rχ=sup⁡{|z|c:z∈supp⁡χ}R_\chi=\sup\{|z|_{\rm c}:z\in\operatorname{supp}\chi\}. For the original fixed metric define λ=|ξλ|g,xλ→∞,wλ†HE(xλ)wλ=1.(PW9) \lambda=|\xi_\lambda|_{g,x_\lambda}\longrightarrow\infty, \qquad w_\lambda^\dagger H_E(x_\lambda)w_\lambda=1. \tag{PW9} The second equality is the meaning of unit vector needed in OM6. It does not require an orthonormal coordinate frame. It gives |wλ|c2≤(hE−)−1|w_\lambda|_{\rm c}^2\leq(h_E^-)^{-1}. For all sufficiently large λ\lambda, the packet support is contained in U0U_0, uniformly over xλ∈Kx_\lambda\in K. The actual section, with the local frame identifications made explicit, is vλ(x)=λn/4χ(λ(x−xλ))ei(x−xλ)⋅ξλwλ|dx|1/2.(PW10) v_\lambda(x)= \lambda^{n/4}\chi\!\left(\sqrt\lambda(x-x_\lambda)\right) e^{\,i(x-x_\lambda)\cdot\xi_\lambda} w_\lambda\,|dx|^{1/2}. \tag{PW10} The local bundle frame multiplying wλw_\lambda is understood in PW10, and the section is extended by zero. Its exact norm is ∥vλ∥L2(E)2=∫|χ(z)|2wλ†HE(xλ+λ−1/2z)wλdz.(PW11) \|v_\lambda\|_{L^2(E)}^2 =\int|\chi(z)|^2 w_\lambda^\dagger H_E(x_\lambda+\lambda^{-1/2}z)w_\lambda\,dz . \tag{PW11} This follows from the exact change dx=λ−n/2dzdx=\lambda^{-n/2}dz; that factor cancels the λn/2\lambda^{n/2} from the squared packet amplitude. The full metric difference is HE(xλ+λ−1/2z)−HE(xλ)=λ−1/2∑j=1nzj∫01∂xjHE(xλ+tλ−1/2z)dt.(PW12) H_E(x_\lambda+\lambda^{-1/2}z)-H_E(x_\lambda) =\lambda^{-1/2}\sum_{j=1}^n z_j \int_0^1\partial_{x_j}H_E (x_\lambda+t\lambda^{-1/2}z)\,dt . \tag{PW12} The segments lie inside the fixed coordinate region for large λ\lambda. PW4, PW9 and PW12 give a uniform O(λ−1/2)O(\lambda^{-1/2}) error in PW11 and therefore ∥vλ∥L2(E)2=1+O(λ−1/2),∥vλ∥L2(E)=1+O(λ−1/2).(PW13) \|v_\lambda\|_{L^2(E)}^2=1+O(\lambda^{-1/2}), \qquad \|v_\lambda\|_{L^2(E)}=1+O(\lambda^{-1/2}). \tag{PW13}

For clarity about another possible half-density presentation, if one writes PW10 relative to ρ(x)=r(x)|dx|1/2\rho(x)=r(x)|dx|^{1/2}, r>0r>0, then its norm is instead ∫|χ(z)|2r(xλ+λ−1/2z)2wλ†HE(xλ+λ−1/2z)wλdz.(PW14) \int|\chi(z)|^2r(x_\lambda+\lambda^{-1/2}z)^2 w_\lambda^\dagger H_E(x_\lambda+\lambda^{-1/2}z)w_\lambda\,dz . \tag{PW14} Under PW9 this tends to r(xλ)2r(x_\lambda)^2, with the same uniform metric-and-density error. Thus PW13 as written requires the coordinate half-density frame, or the explicit center condition r(xλ)2wλ†HE(xλ)wλ=1r(x_\lambda)^2 w_\lambda^\dagger H_E(x_\lambda)w_\lambda=1. If a general frame is used, its rr factor also stays in the Fourier integral; it cannot be silently dropped. The following formulas use the stated coordinate frame PW3.

Writing vλv_\lambda for its coordinate coefficient in PW7, its forward Fourier transform is exactly v̂λ(η)=λ−n/4e−ixλ⋅ηχ̂(η−ξλλ)wλ.(PW15) \widehat v_\lambda(\eta) =\lambda^{-n/4}e^{-ix_\lambda\cdot\eta} \widehat\chi\!\left( \frac{\eta-\xi_\lambda}{\sqrt\lambda}\right)w_\lambda . \tag{PW15} Indeed x=xλ+z/λx=x_\lambda+z/\sqrt\lambda gives −x⋅η+(x−xλ)⋅ξλ=−xλ⋅η−z⋅(η−ξλ)/λ,λn/4dx=λ−n/4dz. -x\cdot\eta+(x-x_\lambda)\cdot\xi_\lambda =-x_\lambda\cdot\eta -z\cdot(\eta-\xi_\lambda)/\sqrt\lambda , \quad \lambda^{n/4}dx=\lambda^{-n/4}dz . In particular the constant phase is e−ixλ⋅ηe^{-ix_\lambda\cdot\eta}. Replacing it by e−ixλ⋅(η−ξλ)e^{-ix_\lambda\cdot(\eta-\xi_\lambda)} would change this original packet by the extra factor eixλ⋅ξλe^{ix_\lambda\cdot\xi_\lambda}. Inverse transformation retains the complete constant: vλ(x)=(2π)−nλn/4ei(x−xλ)⋅ξλ∫eiλ(x−xλ)⋅zχ̂(z)dzwλ.(PW16) v_\lambda(x)= (2\pi)^{-n}\lambda^{n/4} e^{i(x-x_\lambda)\cdot\xi_\lambda} \int e^{i\sqrt\lambda(x-x_\lambda)\cdot z} \widehat\chi(z)\,dz\,w_\lambda . \tag{PW16} Plancherel in these conventions is ∥u∥L2(dx)2=(2π)−n∫|û(η)|2dη\|u\|_{L^2(dx)}^2=(2\pi)^{-n}\int|\widehat u(\eta)|^2d\eta. For every multiindex β\beta, PW15 has the full derivative ∂ηβv̂λ(η)=λ−n/4e−ixλ⋅η∑μ≤β(βμ)(−ixλ)β−μλ−|μ|/2(∂μχ̂)((η−ξλ)/λ)wλ.(PW17) \partial_\eta^\beta\widehat v_\lambda(\eta) =\lambda^{-n/4}e^{-ix_\lambda\cdot\eta} \sum_{\mu\leq\beta}{\beta\choose\mu} (-ix_\lambda)^{\beta-\mu}\lambda^{-|\mu|/2} (\partial^\mu\widehat\chi) ((\eta-\xi_\lambda)/\sqrt\lambda)w_\lambda . \tag{PW17} Every derivative of χ̂\widehat\chi decreases faster than every power: differentiate its defining compact integral and integrate by parts in each original coordinate. No Fourier constant is introduced by that forward transform.

The exact centered differentiation identity is (Dr−ξλ,r)vλ=−iλn/4+1/2(∂rχ)(λ(x−xλ))ei(x−xλ)⋅ξλwλ.(PW18) (D_r-\xi_{\lambda,r})v_\lambda =-i\lambda^{n/4+1/2} (\partial_r\chi)(\sqrt\lambda(x-x_\lambda)) e^{i(x-x_\lambda)\cdot\xi_\lambda}w_\lambda . \tag{PW18} Consequently its Euclidean norm squared is λ|wλ|c2∫|∂rχ|2\lambda|w_\lambda|_{\rm c}^2\int|\partial_r\chi|^2, while its geometric norm squared retains the exact integrand λ∫|∂rχ(z)|2wλ†HE(xλ+λ−1/2z)wλdz.(PW19) \lambda\int|\partial_r\chi(z)|^2 w_\lambda^\dagger H_E(x_\lambda+\lambda^{-1/2}z) w_\lambda\,dz . \tag{PW19} Both yield a uniform O(λ1/2)O(\lambda^{1/2}) norm.

3. The frequency cutoff, all of its derivatives and the tail

Set cg=max⁡(1,κ+)c_g=\max(1,\kappa_+). Choose a fixed ϑ∈Cc∞(ℝn)\vartheta\in C_c^\infty(\mathbb R^n), equal to one when |q|c≤1/2|q|_{\rm c}\leq1/2, supported where |q|c≤1|q|_{\rm c}\leq1, and with 0≤ϑ≤10\leq\vartheta\leq1. Define qλ(η)=2cgλ(η−ξλ),ϑλ(η)=ϑ(qλ(η)),tλ=(1−ϑλ)(D)vλ.(PW20) q_\lambda(\eta)=\frac{2c_g}{\lambda}(\eta-\xi_\lambda), \quad \vartheta_\lambda(\eta)=\vartheta(q_\lambda(\eta)), \quad t_\lambda=(1-\vartheta_\lambda)(D)v_\lambda . \tag{PW20} This keeps λ\lambda as the original metric norm. The cutoff support has |η−ξλ|c≤λ/(2cg)|\eta-\xi_\lambda|_{\rm c}\leq\lambda/(2c_g). When λ\lambda is a coordinate norm and cg=1c_g=1, this is the radius λ/2\lambda/2 stated in the original OM8 discussion. For a general metric PW20 records the needed chart constant. On that support, for every 0≤θ≤10\leq\theta\leq1, |ξλ+θ(η−ξλ)|c≥λ/κ+−λ/(2cg)≥λ/(2cg),|η|c≤λ/κ−+λ/(2cg).(PW21) |\xi_\lambda+\theta(\eta-\xi_\lambda)|_{\rm c} \geq \lambda/\kappa_+-\lambda/(2c_g) \geq \lambda/(2c_g),\qquad |\eta|_{\rm c}\leq\lambda/\kappa_-+\lambda/(2c_g). \tag{PW21} Every derivative of the cutoff is exactly ∂ηγϑλ=(2cg)|γ|λ−|γ|(∂γϑ)(qλ).(PW22) \partial_\eta^\gamma\vartheta_\lambda =(2c_g)^{|\gamma|}\lambda^{-|\gamma|} (\partial^\gamma\vartheta)(q_\lambda). \tag{PW22} It is supported in the same fixed-radius rescaled ball. Every positive-order derivative of 1−ϑλ1-\vartheta_\lambda is the negative of PW22; its zeroth derivative is 1−ϑλ1-\vartheta_\lambda. Thus every tail-transform derivative is exactly the product sum ∂ηβt̂λ=∑γ≤β(βγ)∂ηγ(1−ϑλ)∂ηβ−γv̂λ,(PW23) \partial_\eta^\beta\widehat t_\lambda =\sum_{\gamma\leq\beta}{\beta\choose\gamma} \partial_\eta^\gamma(1-\vartheta_\lambda) \partial_\eta^{\beta-\gamma}\widehat v_\lambda , \tag{PW23} with PW17 and PW22 supplying all factors and signs.

For every fixed real ss, the tail’s exact Euclidean Sobolev norm is ∥tλ∥Hs(ℝn)2=(2π)−n|wλ|c2∫⟨ξλ+λz⟩c2s|1−ϑ(2cgz/λ)|2|χ̂(z)|2dz.(PW24) \begin{split} \|t_\lambda\|_{H^s(\mathbb R^n)}^2 &=(2\pi)^{-n}|w_\lambda|_{\rm c}^2 \int \langle\xi_\lambda+\sqrt\lambda z\rangle_{\rm c}^{2s} |1-\vartheta(2c_g z/\sqrt\lambda)|^2 |\widehat\chi(z)|^2\,dz . \end{split} \tag{PW24} The two powers λ−n/2\lambda^{-n/2} and λn/2\lambda^{n/2} from PW15 and dηd\eta cancel exactly. The nonzero integrand has |z|c≥λ/(4cg)|z|_{\rm c}\geq\sqrt\lambda/(4c_g). Put s+=max⁡(s,0)s_+=\max(s,0). For λ≥1\lambda\geq1, ⟨ξλ+λz⟩c≤2(1+κ−−1)λ⟨z⟩c.(PW25) \langle\xi_\lambda+\sqrt\lambda z\rangle_{\rm c} \leq \sqrt2(1+\kappa_-^{-1})\lambda \langle z\rangle_{\rm c}. \tag{PW25} Use |χ̂(z)|≤CL⟨z⟩c−L|\widehat\chi(z)|\leq C_L\langle z\rangle_{\rm c}^{-L}. For λ≥(4cg)2\lambda\geq(4c_g)^2 and 2(L−s+)>n2(L-s_+)>n, integration outside the displayed ball gives ∥tλ∥Hs2≤Cs,Lλ3s++n/2−L.(PW26) \|t_\lambda\|_{H^s}^2 \leq C_{s,L}\lambda^{3s_++n/2-L}. \tag{PW26} For example this follows by comparison with ∫R∞rn−1−2(L−s+)dr=Rn−2(L−s+)/(2(L−s+)−n)\int_R^\infty r^{n-1-2(L-s_+)}dr =R^{n-2(L-s_+)}/(2(L-s_+)-n), multiplied by the sphere area; here R=λ/(4cg)R=\sqrt\lambda/(4c_g). All constants from PW24–PW25 remain in Cs,LC_{s,L}. For each fixed ss and NN, choosing L>2N+3s++n/2L>2N+3s_++n/2 proves ∥tλ∥Hs=O(λ−N).(PW27) \|t_\lambda\|_{H^s}=O(\lambda^{-N}). \tag{PW27} This is uniform in the centers, directions and metric-unit vectors. It also keeps all centered differentiation factors: for a fixed multiindex δ\delta, replace PW24’s integrand by λ|δ||zδ|2\lambda^{|\delta|}|z^\delta|^2 times that integrand to obtain ∥(D−ξλ)δtλ∥Hs2≤Cs,L,δλ3s++2|δ|+n/2−L.(PW28) \|(D-\xi_\lambda)^\delta t_\lambda\|_{H^s}^2 \leq C_{s,L,\delta} \lambda^{3s_++2|\delta|+n/2-L}. \tag{PW28} Thus these tail terms decrease faster than every prescribed power as well.

4. Every derivative of the mean-value coefficient

The exact identity OM8, now for the cutoff-extended symbol, is ã(x,η)−ã(x,ξλ)=∑r=1n(ηr−ξλ,r)∫01∂ηrã(x,ξλ+θ(η−ξλ))dθ.(PW29) \widetilde a(x,\eta)-\widetilde a(x,\xi_\lambda) =\sum_{r=1}^n(\eta_r-\xi_{\lambda,r}) \int_0^1\partial_{\eta_r}\widetilde a (x,\xi_\lambda+\theta(\eta-\xi_\lambda))\,d\theta . \tag{PW29} Define the actual cutoff coefficients bλ,r(x,η)=ϑλ(η)∫01∂ηrã(x,ξλ+θ(η−ξλ))dθ.(PW30) b_{\lambda,r}(x,\eta)=\vartheta_\lambda(\eta) \int_0^1\partial_{\eta_r}\widetilde a (x,\xi_\lambda+\theta(\eta-\xi_\lambda))\,d\theta . \tag{PW30} For all multiindices α,β\alpha,\beta, their complete derivative formula is ∂xα∂ηβbλ,r=∑γ≤β(βγ)(2cg)|γ|λ−|γ|(∂γϑ)(qλ)×∫01θ|β−γ|(∂xα∂ηβ−γ+erã)(x,ξλ+θ(η−ξλ))dθ.(PW31) \begin{split} \partial_x^\alpha\partial_\eta^\beta b_{\lambda,r} &=\sum_{\gamma\leq\beta}{\beta\choose\gamma} (2c_g)^{|\gamma|}\lambda^{-|\gamma|} (\partial^\gamma\vartheta)(q_\lambda)\\ &\quad{}\times\int_0^1\theta^{|\beta-\gamma|} (\partial_x^\alpha \partial_\eta^{\beta-\gamma+e_r}\widetilde a) (x,\xi_\lambda+\theta(\eta-\xi_\lambda))\,d\theta . \end{split} \tag{PW31} If desired, substitute PW8 into the last line to retain each individual output-cutoff derivative as well. Each factor θ|β−γ|\theta^{|\beta-\gamma|} comes from differentiating the affine frequency path; there is no derivative of either center parameter, because these are fixed parameters when differentiating x,ηx,\eta. The binomial coefficients include every way derivatives can hit the frequency cutoff. Differentiation under the integral is justified on the compact interval by the smooth integrand and its uniform bounds PW6 and PW21.

Every nonzero term in PW31 is supported where PW21 holds. Consequently ∥∂xα∂ηβbλ,r∥∞≤(2cg)1+|β|λ−1−|β|∑γ≤β(βγ)∥∂γϑ∥∞M̃α,β−γ+er1+|β−γ|.(PW32) \begin{split} \|\partial_x^\alpha\partial_\eta^\beta b_{\lambda,r}\|_\infty &\leq (2c_g)^{1+|\beta|} \lambda^{-1-|\beta|} \sum_{\gamma\leq\beta}{\beta\choose\gamma} \|\partial^\gamma\vartheta\|_\infty \frac{\widetilde M_{\alpha,\beta-\gamma+e_r}} {1+|\beta-\gamma|}. \end{split} \tag{PW32} Here the denominator is the exact integral ∫01θ|β−γ|dθ\int_0^1\theta^{|\beta-\gamma|}d\theta. The factor (2cg)1+|β|(2c_g)^{1+|\beta|} is the product of the cutoff factor in PW31 and the lower-frequency comparison in PW21. In particular bλ,rb_{\lambda,r} is a uniformly bounded family in S1,0−1S^{-1}_{1,0}, and λbλ,r\lambda b_{\lambda,r} is a uniformly bounded family in S1,00S^0_{1,0}: on its support ⟨η⟩c≤(1+κ−−1+(2cg)−1)λ\langle\eta\rangle_{\rm c}\leq (1+\kappa_-^{-1}+(2c_g)^{-1})\lambda, and outside that support all derivatives vanish. More directly, E23 and PW32 give ∥Op⁡(bλ,r)u∥L2(dx)≤Cnmax|α|+|β|≤Ln∥∂xα∂ηβbλ,r∥∞∥u∥L2(dx)≤Crλ−1∥u∥L2(dx).(PW33) \|\operatorname{Op}(b_{\lambda,r})u\|_{L^2(dx)} \leq C_n \max_{|\alpha|+|\beta|\leq L_n} \|\partial_x^\alpha\partial_\eta^\beta b_{\lambda,r}\|_\infty \|u\|_{L^2(dx)} \leq C_r\lambda^{-1}\|u\|_{L^2(dx)} . \tag{PW33} This uses a fixed derivative count and finitely many original symbol seminorms. It is therefore uniform, rather than a separate boundedness assertion for each λ\lambda.

5. Ordered decomposition and the spatial term

Let Mã(⋅,ξλ)M_{\widetilde a(\cdot,\xi_\lambda)} denote multiplication by the actual xx-dependent matrix. PW29 gives the exact operator identity on the packet Op⁡(ã)vλ−Mã(⋅,ξλ)vλ=∑r=1nOp⁡(bλ,r)(Dr−ξλ,r)vλ+Op⁡(ã)tλ−Mã(⋅,ξλ)tλ.(PW34) \begin{split} \operatorname{Op}(\widetilde a)v_\lambda -M_{\widetilde a(\cdot,\xi_\lambda)}v_\lambda &=\sum_{r=1}^n \operatorname{Op}(b_{\lambda,r}) (D_r-\xi_{\lambda,r})v_\lambda\\ &\quad{}+\operatorname{Op}(\widetilde a)t_\lambda -M_{\widetilde a(\cdot,\xi_\lambda)}t_\lambda . \end{split} \tag{PW34} To check every product in this identity, transform the rightmost (Dr−ξλ,r)vλ(D_r-\xi_{\lambda,r})v_\lambda. Its transform is exactly (ηr−ξλ,r)v̂λ(\eta_r-\xi_{\lambda,r})\widehat v_\lambda. Thus the first line of PW34 has left symbol (ã(x,η)−ã(x,ξλ))ϑλ(η)(\widetilde a(x,\eta)-\widetilde a(x,\xi_\lambda)) \vartheta_\lambda(\eta). The second line has the same difference times 1−ϑλ(η)1-\vartheta_\lambda(\eta). Their sum is the original left-symbol difference. The derivative operator stands on the right; no matrix factor is commuted, and no composition correction is discarded.

E23 also bounds the fixed operator Op⁡(ã)\operatorname{Op}(\widetilde a). Multiplication by ã(x,ξλ)\widetilde a(x,\xi_\lambda) is bounded uniformly by PW6 and PW8. Hence PW18, PW27 and PW33 prove ∥Op⁡(ã)vλ−Mã(⋅,ξλ)vλ∥L2(dx)≤Cλ−1/2.(PW35) \|\operatorname{Op}(\widetilde a)v_\lambda -M_{\widetilde a(\cdot,\xi_\lambda)}v_\lambda\|_{L^2(dx)} \leq C\lambda^{-1/2}. \tag{PW35} The output is supported in the fixed support of ζ\zeta; the factor HFH_F in PW3 converts this to the geometric norm with the factor (hF+)1/2(h_F^+)^{1/2}. The input norms in PW33 and PW18 likewise retain PW4’s uniform coordinate comparison.

Let the frozen output section be fλ(x)=λn/4χ(λ(x−xλ))ei(x−xλ)⋅ξλa(xλ,ξλ)wλ|dx|1/2,(PW36) f_\lambda(x)= \lambda^{n/4}\chi(\sqrt\lambda(x-x_\lambda)) e^{i(x-x_\lambda)\cdot\xi_\lambda} a(x_\lambda,\xi_\lambda)w_\lambda\,|dx|^{1/2}, \tag{PW36} using the specified output frame. This is the precise meaning of a(xλ,ξλ)vλa(x_\lambda,\xi_\lambda)v_\lambda in OM7: the constant coordinate matrix sends the input coordinates to the output coordinates. It does not identify ExE_x with FxF_x. On the support of vλv_\lambda, ζ=1\zeta=1 and a(x,ξλ)−a(xλ,ξλ)=∑j=1n(xj−xλ,j)∫01∂xja(xλ+t(x−xλ),ξλ)dt.(PW37) a(x,\xi_\lambda)-a(x_\lambda,\xi_\lambda) =\sum_{j=1}^n(x_j-x_{\lambda,j}) \int_0^1\partial_{x_j}a (x_\lambda+t(x-x_\lambda),\xi_\lambda)\,dt . \tag{PW37} PW6, PW9, PW11 and the compact support of χ\chi give ∥Mã(⋅,ξλ)vλ−fλ∥L2(F)≤Cλ−1/2(∫|z|c2|χ(z)|2dz)1/2.(PW38) \|M_{\widetilde a(\cdot,\xi_\lambda)}v_\lambda -f_\lambda\|_{L^2(F)} \leq C\lambda^{-1/2} \left(\int |z|_{\rm c}^2|\chi(z)|^2dz\right)^{1/2}. \tag{PW38} All the spatial factors and the target metric remain in this estimate. Writing zλ=a(xλ,ξλ)wλz_\lambda=a(x_\lambda,\xi_\lambda)w_\lambda, its frozen output norm is exactly ∥fλ∥L2(F)2=∫|χ(z)|2zλ†HF(xλ+λ−1/2z)zλdz.(PW39) \|f_\lambda\|_{L^2(F)}^2 =\int|\chi(z)|^2 z_\lambda^\dagger H_F(x_\lambda+\lambda^{-1/2}z) z_\lambda\,dz . \tag{PW39} The target version of PW12 and PW4 give |∥fλ∥L2(F)2−∥a(xλ,ξλ)wλ∥Fxλ2|≤Cλ−1/2∥a(xλ,ξλ)wλ∥Fxλ2.(PW40) \left|\|f_\lambda\|_{L^2(F)}^2 -\|a(x_\lambda,\xi_\lambda)w_\lambda\|_{F_{x_\lambda}}^2\right| \leq C\lambda^{-1/2} \|a(x_\lambda,\xi_\lambda)w_\lambda\|_{F_{x_\lambda}}^2 . \tag{PW40} This relative estimate includes the case zλ=0z_\lambda=0, when both sides vanish exactly.

6. The off-diagonal kernel and every smoothing contribution

For large λ\lambda, ψvλ=vλ\psi v_\lambda=v_\lambda. The exact localized decomposition is Avλ=Op⁡(ã)vλ+Rvλ+(1−ζ)Aψvλ.(PW41) Av_\lambda =\operatorname{Op}(\widetilde a)v_\lambda +Rv_\lambda+(1-\zeta)A\psi v_\lambda . \tag{PW41} The RR term has a smooth localized kernel by its definition. The last term has a smooth kernel because the supports of 1−ζ1-\zeta and ψ\psi are separated. This also follows directly from the full local Fourier kernel, with all signs retained. For z=x−y≠0z=x-y\ne0, E12 and distributional frequency integration by parts give ∂xα∂yβKa(x,y)=(2π)−n|x−y|c−2M∑γ≤α(αγ)∫ei(x−y)⋅η×(−Δη)M[(iη)α−γ(−iη)β∂xγa(x,η)]dη.(PW42) \begin{split} \partial_x^\alpha\partial_y^\beta K_a(x,y) &=(2\pi)^{-n}|x-y|_{\rm c}^{-2M} \sum_{\gamma\leq\alpha}{\alpha\choose\gamma} \int e^{i(x-y)\cdot\eta}\\ &\quad{}\times(-\Delta_\eta)^M \left[(i\eta)^{\alpha-\gamma}(-i\eta)^\beta \partial_x^\gamma a(x,\eta)\right]\,d\eta . \end{split} \tag{PW42} Choose 2M>n+|α|+|β|2M>n+|\alpha|+|\beta|. The full differentiated amplitude is (−Δη)M[Pα,β,γ(η)∂xγa]=(−1)M∑|ν|=MM!ν!∑δ≤2ν(2νδ)(∂η2ν−δPα,β,γ)×(∂ηδ∂xγa),Pα,β,γ=(iη)α−γ(−iη)β.(PW43) \begin{split} (-\Delta_\eta)^M [P_{\alpha,\beta,\gamma}(\eta)\partial_x^\gamma a] &=(-1)^M\sum_{|\nu|=M}\frac{M!}{\nu!} \sum_{\delta\leq2\nu}{2\nu\choose\delta} (\partial_\eta^{2\nu-\delta} P_{\alpha,\beta,\gamma})\\ &\qquad{}\times (\partial_\eta^\delta\partial_x^\gamma a), \quad P_{\alpha,\beta,\gamma} =(i\eta)^{\alpha-\gamma}(-i\eta)^\beta . \end{split} \tag{PW43} Its nonzero terms have frequency bound C⟨η⟩c|α−γ|+|β|−2MC\langle\eta\rangle_{\rm c}^{|\alpha-\gamma|+|\beta|-2M}, which is integrable. For a monomial ∂ητηω\partial_\eta^\tau\eta^\omega equals ω!ηω−τ/(ω−τ)!\omega!\eta^{\omega-\tau}/(\omega-\tau)! when τ≤ω\tau\leq\omega, and is zero otherwise; thus PW43 keeps the full coefficient and every zero. The original inverse factor (2π)−n(2\pi)^{-n} and both differentiation signs stay in PW42. The distributional identities E12 and EC15 justify PW42 before any assertion of absolute convergence. Multiplication by |x−y|c−2M|x-y|_{\rm c}^{-2M} is smooth away from z=0z=0; the integrable amplitude then identifies the resulting restriction. Here is also the full compact-cutoff passage. Choose a fixed smooth ω\omega, equal to one on |η|c≤c0|\eta|_{\rm c}\leq c_0 and zero on |η|c≥c1|\eta|_{\rm c}\geq c_1, with 0<c0<c10<c_0<c_1. Put B=Pα,β,γ∂xγaB=P_{\alpha,\beta,\gamma}\partial_x^\gamma a and d=|α−γ|+|β|d=|\alpha-\gamma|+|\beta|. For every ν\nu in PW43, ∂η2ν[B(x,η)ω(η/R)]=∑σ≤2ν(2νσ)(∂η2ν−σB)(x,η)R−|σ|(∂σω)(η/R).(PW43a) \partial_\eta^{2\nu}[B(x,\eta)\omega(\eta/R)] =\sum_{\sigma\leq2\nu}{2\nu\choose\sigma} (\partial_\eta^{2\nu-\sigma}B)(x,\eta) R^{-|\sigma|}(\partial^\sigma\omega)(\eta/R). \tag{PW43a} The derivatives of BB have their full product-rule sums as in PW43, with the corresponding total derivative order. The σ=0\sigma=0 term tends to ∂η2νB\partial_\eta^{2\nu}B in absolute integral by its integrable bound. Every σ>0\sigma>0 term has the original annular support c0R≤|η|c≤c1Rc_0R\leq|\eta|_{\rm c}\leq c_1R, and its absolute integral has the bound (2νσ)R−|σ|∥∂σω∥∞∫c0R≤|η|c≤c1RCν,σ⟨η⟩cd−2M+|σ|dη≤Cν,σ′Rn+d−2M→0.(PW43b) {2\nu\choose\sigma}R^{-|\sigma|} \|\partial^\sigma\omega\|_\infty \int_{c_0R\leq|\eta|_{\rm c}\leq c_1R} C_{\nu,\sigma}\langle\eta\rangle_{\rm c}^{d-2M+|\sigma|}d\eta \leq C'_{\nu,\sigma}R^{n+d-2M}\longrightarrow0. \tag{PW43b} The constants include the annulus volume ωnc1nRn\omega_nc_1^nR^n, c0,c1c_0,c_1 and all polynomial coefficients. The exponent is negative by the stated choice of MM. Thus every frequency-cutoff derivative vanishes separately, and the original oscillatory identity passes to PW42 with all boundary terms accounted for. For every pair α,β\alpha,\beta, this is a continuous derivative. Consequently the kernel is smooth away from the coordinate diagonal. For output cutoff c(x)c(x) and input cutoff d(y)d(y), the exact remaining derivative sum is ∂xα∂yβ[c(x)Ka(x,y)d(y)]=∑ρ≤α∑σ≤β(αρ)(βσ)(∂xρc)(x)(∂xα−ρ∂yβ−σKa)(x,y)(∂yσd)(y).(PW43c) \partial_x^\alpha\partial_y^\beta[c(x)K_a(x,y)d(y)] =\sum_{\rho\leq\alpha}\sum_{\sigma\leq\beta} {\alpha\choose\rho}{\beta\choose\sigma} (\partial_x^\rho c)(x) (\partial_x^{\alpha-\rho}\partial_y^{\beta-\sigma}K_a)(x,y) (\partial_y^\sigma d)(y). \tag{PW43c} For the actual off-diagonal term, c=1−ζc=1-\zeta, d=ψd=\psi: the zeroth output derivative is 1−ζ1-\zeta, and each positive output derivative is −∂xρζ-\partial_x^\rho\zeta. All such contributions retain the smooth-kernel bounds just proved. In other charts the same argument applies. Compactness and the positive support separation give uniform bounds for the resulting global smooth kernel and all its input and output derivatives.

Here is the exact packet bound for any such smooth matrix kernel S(x,y)S(x,y). Its local action on the actual coordinate half-density coefficient is Svλ(x)=λn/4∫S(x,y)χ(λ(y−xλ))ei(y−xλ)⋅ξλwλdy.(PW44) Sv_\lambda(x)=\lambda^{n/4} \int S(x,y)\chi(\sqrt\lambda(y-x_\lambda)) e^{i(y-x_\lambda)\cdot\xi_\lambda}w_\lambda\,dy . \tag{PW44} The input integration measure is precisely dydy; the kernel’s half-density factors produce the output half-density as in PW3. Set Lλ=ξλ⋅∂yi|ξλ|c2;Lλei(y−xλ)⋅ξλ=ei(y−xλ)⋅ξλ.(PW45) L_\lambda=\frac{\xi_\lambda\cdot\partial_y} {i|\xi_\lambda|_{\rm c}^2}; \qquad L_\lambda e^{i(y-x_\lambda)\cdot\xi_\lambda} =e^{i(y-x_\lambda)\cdot\xi_\lambda}. \tag{PW45} Compact support of the packet envelope removes all input boundary terms. Repeated integration by parts gives the exact finite sum Svλ(x)=λn/4(−1)M(i|ξλ|c2)M∑|γ|=MM!γ!ξλγ∑δ≤γ(γδ)λ|δ|/2×∫ei(y−xλ)⋅ξλ(∂yγ−δS)(x,y)(∂δχ)(λ(y−xλ))wλdy.(PW46) \begin{split} Sv_\lambda(x) &=\frac{\lambda^{n/4}(-1)^M} {(i|\xi_\lambda|_{\rm c}^2)^M} \sum_{|\gamma|=M}\frac{M!}{\gamma!}\xi_\lambda^\gamma \sum_{\delta\leq\gamma}{\gamma\choose\delta} \lambda^{|\delta|/2}\\ &\quad{}\times\int e^{i(y-x_\lambda)\cdot\xi_\lambda} (\partial_y^{\gamma-\delta}S)(x,y) (\partial^\delta\chi)(\sqrt\lambda(y-x_\lambda)) w_\lambda\,dy . \end{split} \tag{PW46} The sign (−1)M(-1)^M, denominator iMi^M, multinomial coefficients and all envelope derivatives remain visible. Every fixed output derivative has the same formula with the corresponding derivative of SS. PW5 gives |ξλγ||ξλ|c2M≤|ξλ|c−M≤κ+Mλ−M. \frac{|\xi_\lambda^\gamma|} {|\xi_\lambda|_{\rm c}^{2M}} \leq|\xi_\lambda|_{\rm c}^{-M} \leq\kappa_+^M\lambda^{-M}. The envelope’s exact L1L^1 integral is λ−n/2∥∂δχ∥1\lambda^{-n/2}\|\partial^\delta\chi\|_1. Using PW9 in PW46 therefore yields, for every fixed output derivative order, ∥∂xαSvλ∥∞≤Cα,Mλ−M/2−n/4.(PW47) \|\partial_x^\alpha Sv_\lambda\|_\infty \leq C_{\alpha,M}\lambda^{-M/2-n/4}. \tag{PW47} Finitely many output charts, the retained smooth metrics and the finite volume of XX convert this to geometric L2L^2. For each requested power NN, choose M≥2NM\geq2N to obtain ∥Rvλ∥L2(F)+∥(1−ζ)Aψvλ∥L2(F)=O(λ−N).(PW48) \|Rv_\lambda\|_{L^2(F)} +\|(1-\zeta)A\psi v_\lambda\|_{L^2(F)} =O(\lambda^{-N}). \tag{PW48} The proof applies separately to every smooth remainder; none is absorbed into the symbol error without an estimate.

PW35, PW38, PW41 and PW48 prove the required full estimate ∥Avλ−fλ∥L2(F)≤Cλ−1/2.(PW49) \boxed{\ \|Av_\lambda-f_\lambda\|_{L^2(F)} \leq C\lambda^{-1/2}\ } . \tag{PW49} The constant depends only on the fixed chart, cutoffs, metric bounds, profile and finitely many symbol seminorms. It is independent of the moving center, covector direction, frequency and metric-unit vector.

7. Weak convergence, order-minus-one errors and uniform necessity

The support is contained in the coordinate ball B(xλ,Rχ/λ)B(x_\lambda,R_\chi/\sqrt\lambda), whose coordinate volume is ωnRχnλ−n/2\omega_nR_\chi^n\lambda^{-n/2}. For any fixed g∈L2(E)g\in L^2(E), geometric Cauchy–Schwarz gives |⟨vλ,g⟩L2(E)|≤∥vλ∥L2(E)∥𝟏supp⁡vλg∥L2(E)→0.(PW50) |\langle v_\lambda,g\rangle_{L^2(E)}| \leq \|v_\lambda\|_{L^2(E)} \|\mathbf1_{\operatorname{supp}v_\lambda}g\|_{L^2(E)} \longrightarrow0. \tag{PW50} Absolute continuity of the integral of g†HEgg^\dagger H_Eg proves the convergence for these moving sets, uniformly with respect to their centers. PW13 bounds the first factor. Thus the original packets are weakly null.

For completeness let ℛ∈Ψ1,0−1(X;E,F)\mathcal R\in\Psi^{-1}_{1,0}(X;E,F), let r∈S1,0−1r\in S^{-1}_{1,0} be its complete local symbol, and retain its localized smooth remainder and off-diagonal term. In the following Euclidean formulas use r=ζrlocr=\zeta r_{\rm loc}, extended by zero, exactly as in PW8. Thus each base derivative contains the full sum of derivatives of ζ\zeta and of the original complete symbol rlocr_{\rm loc}; at the packet center the two symbols coincide. Its cutoff symbol has every derivative ∂xα∂ηβ[r(x,η)ϑλ(η)]=∑γ≤β(βγ)(∂xα∂ηβ−γr)(x,η)(2cg)|γ|λ−|γ|(∂γϑ)(qλ).(PW51) \partial_x^\alpha\partial_\eta^\beta [r(x,\eta)\vartheta_\lambda(\eta)] =\sum_{\gamma\leq\beta}{\beta\choose\gamma} (\partial_x^\alpha\partial_\eta^{\beta-\gamma}r)(x,\eta) (2c_g)^{|\gamma|}\lambda^{-|\gamma|} (\partial^\gamma\vartheta)(q_\lambda). \tag{PW51} On this support PW21 gives ⟨η⟩c≥λ/(2cg)\langle\eta\rangle_{\rm c}\geq\lambda/(2c_g). Hence each full derivative in PW51 is O(λ−1−|β|)O(\lambda^{-1-|\beta|}), with its finite binomial sum retained. E23 then bounds Op⁡(rϑλ)\operatorname{Op}(r\vartheta_\lambda) by Cλ−1C\lambda^{-1}. The exact tail decomposition Op⁡(r)vλ=Op⁡(rϑλ)vλ+Op⁡(r)tλ(PW52) \operatorname{Op}(r)v_\lambda =\operatorname{Op}(r\vartheta_\lambda)v_\lambda +\operatorname{Op}(r)t_\lambda \tag{PW52} and PW27, together with PW48 for the smoothing term, prove ∥ℛvλ∥L2(F)=O(λ−1)for each fixed ℛ∈Ψ1,0−1(X;E,F).(PW53) \|\mathcal Rv_\lambda\|_{L^2(F)}=O(\lambda^{-1}) \quad\text{for each fixed }\mathcal R\in\Psi^{-1}_{1,0}(X;E,F). \tag{PW53} Here ℛ\mathcal R is distinct from the smooth local remainder RR of PW41.

Every point of XX lies in one member of a finite cover by smaller coordinate regions KK of the kind used above. Taking the maximum of their finitely many constants proves uniformity on XX. For the contradiction argument one can instead select a subsequence whose centers all lie in one such compact smaller region. The original metric frequency λ\lambda is retained on each chart through PW5 and PW20.

Apply this to the exact operator in OM9, As=JE−s:L2(E)→Hs(E),Bs−m=JFs−m:Hs−m(F)→L2(F),T=Bs−mPsAs.(PW54) A_s=J_E^{-s}:L^2(E)\longrightarrow H^s(E),\qquad B_{s-m}=J_F^{s-m}:H^{s-m}(F)\longrightarrow L^2(F),\qquad T=B_{s-m}P_sA_s . \tag{PW54} These are the specified bounded isomorphisms, with their original source and target spaces, metrics and half-densities. Retain the ordered original principal factors p̃(x,ξ)=⟨ξ⟩g,xs−mp(x,ξ)⟨ξ⟩g,x−s.(PW55) \widetilde p(x,\xi) =\langle\xi\rangle_{g,x}^{\,s-m} p(x,\xi)\langle\xi\rangle_{g,x}^{-s}. \tag{PW55} The full local symbol of TT equals this representative plus r∈S1,0−1r\in S^{-1}_{1,0}, including all the lower-order composition terms. PW53 estimates that complete error; it is not presumed zero. The scalar factors in PW55 are positive and the displayed ordered product has the exact value ⟨ξ⟩g,x−mp(x,ξ)\langle\xi\rangle_{g,x}^{-m}p(x,\xi). This equality is an explicit comparison with the original pp; it does not remove pp, its order or either operator factor.

If OM2 fails, choose for each integer jj a covector (xj,ξj)(x_j,\xi_j) with |ξj|g,xj≥j|\xi_j|_{g,x_j}\geq j and a vector ∥wj∥Exj=1\|w_j\|_{E_{x_j}}=1 such that ∥p̃(xj,ξj)wj∥Fxj<1/j.(PW56) \|\widetilde p(x_j,\xi_j)w_j\|_{F_{x_j}}<1/j . \tag{PW56} The failure of a uniform positive lower bound gives exactly these choices. Passing to one smaller chart preserves PW9, with λj=|ξj|g,xj→∞\lambda_j=|\xi_j|_{g,x_j}\to\infty. PW49, PW40 and PW53 give ∥Tvλj∥2→0\|Tv_{\lambda_j}\|_2\to0, while PW13 gives ∥vλj∥2→1\|v_{\lambda_j}\|_2\to1. If N=ker⁡TN=\ker T is finite dimensional, its orthogonal projection sends PW50’s weakly null packets to zero in norm: for an actual orthonormal basis e1,…,ede_1,\ldots,e_d of NN, ∥ΠNvλj∥22=∑ℓ=1d|⟨vλj,eℓ⟩|2→0.(PW57) \|\Pi_Nv_{\lambda_j}\|_2^2 =\sum_{\ell=1}^d |\langle v_{\lambda_j},e_\ell\rangle|^2\longrightarrow0. \tag{PW57} No smoothness of NN is required. Closed range and finite kernel of PsP_s pass through PW54 to TT, so the already-proved compact estimate OM4 gives ∥vλj∥2≤C(∥Tvλj∥2+∥ΠNvλj∥2)→0.(PW58) \|v_{\lambda_j}\|_2 \leq C\bigl(\|Tv_{\lambda_j}\|_2+ \|\Pi_Nv_{\lambda_j}\|_2\bigr)\longrightarrow0. \tag{PW58} This contradicts PW13 and proves OM2 for the original symbol pp with its original weight ⟨ξ⟩g,xm\langle\xi\rangle_{g,x}^{m}. The proof uses the complete S1,00S^0_{1,0} high-frequency symbol and does not require a homogeneous cosphere representative.

Use the actual order-changing bundle isomorphisms proved in the linked global-index lesson: As=JE−s:L2(E)→≅Hs(E),Bs−m=JFs−m:Hs−m(F)→≅L2(F),T=Bs−mPsAs.(OM9) A_s=J_E^{-s}:L^2(E)\xrightarrow{\;\cong\;}H^s(E),\quad B_{s-m}=J_F^{s-m}:H^{s-m}(F)\xrightarrow{\;\cong\;}L^2(F),\quad T=B_{s-m}P_sA_s. \tag{OM9} They are auxiliary comparison maps, not replacements for PsP_s. Their positive scalar principal symbols are ⟨ξ⟩−sIE\langle\xi\rangle^{-s}I_E and ⟨ξ⟩s−mIF\langle\xi\rangle^{s-m}I_F. Keeping all factors and their order gives σ0(T)(x,ξ)=⟨ξ⟩s−mp(x,ξ)⟨ξ⟩−s=⟨ξ⟩−mp(x,ξ)(mod⁡S−1).(OM10) \sigma_0(T)(x,\xi) =\langle\xi\rangle^{s-m}p(x,\xi)\langle\xi\rangle^{-s} =\langle\xi\rangle^{-m}p(x,\xi) \pmod {S^{-1}}. \tag{OM10} Because As,Bs−mA_s,B_{s-m} are exact isomorphisms, TT has finite kernel and closed range. If (OM2) failed, choose (xλ,ξλ,wλ)(x_\lambda,\xi_\lambda,w_\lambda) with λ→∞\lambda\to\infty and ∥⟨ξλ⟩−mp(xλ,ξλ)wλ∥→0\|\langle\xi_\lambda\rangle^{-m}p(x_\lambda,\xi_\lambda)w_\lambda\|\to0. After a subsequence the centers lie in one smaller chart. Apply (OM7) to TT; its S−1S^{-1} difference from the displayed principal map tends to zero on the packets. Thus ∥Tvλ∥2→0\|Tv_\lambda\|_2\to0, while ∥vλ∥2→1\|v_\lambda\|_2\to1 and the finite-rank projection onto ker⁡T\ker T sends the weakly null packets to zero in norm. Equation (OM4) for TT is contradicted. Therefore (OM2) holds. This proves the symbol lower bound directly for the original pp, for an arbitrary real realization order ss.

4. The exact left symbol and the full left parametrix

Assume (OM2). In the actual Hermitian metrics define G=p*pG=p^*p, a positive endomorphism of EE. At large |ξ||\xi|, ⟨Gw,w⟩=∥pw∥2≥c2⟨ξ⟩2m∥w∥2,q0=G−1p*:F→E,q0p=IE.(OM11) \langle Gw,w\rangle=\|pw\|^2 \ge c^2\langle\xi\rangle^{2m}\|w\|^2,\quad q_0=G^{-1}p^*:F\longrightarrow E,\quad q_0p=I_E. \tag{OM11} The full matrix GG remains present. Its symbol derivatives satisfy ∂xα∂ξβG=O(⟨ξ⟩2m−|β|)\partial_x^\alpha\partial_\xi^\beta G =O(\langle\xi\rangle^{2m-|\beta|}). Differentiating GG−1=IEGG^{-1}=I_E and retaining each ordered product yields by induction ∂xα∂ξβG−1=O(⟨ξ⟩−2m−|β|)\partial_x^\alpha\partial_\xi^\beta G^{-1} =O(\langle\xi\rangle^{-2m-|\beta|}). Consequently q0∈S−m(Hom⁡(F,E))q_0\in S^{-m}(\operatorname{Hom}(F,E)). A smooth scalar cutoff in the fixed cotangent norm, zero below the high-frequency region and one beyond a larger region, extends q0q_0 to a global symbol q∈S−mq\in S^{-m} with qp−IE∈S−∞⊂S−1.(OM12) qp-I_E\in S^{-\infty}\subset S^{-1}. \tag{OM12} The construction is invariant under unitary changes of frame because p*pp^*p and its inverse are bundle maps; the cutoff and finite chart quantization preserve the global symbol class.

Here is the complete derivative calculation behind that construction. In a fixed pair of local frames write the original metrics as hE(w,v)=v¯THE(x)wh_E(w,v)=\overline v^{\,T}H_E(x)w and hF(z,y)=y¯THF(x)zh_F(z,y)=\overline y^{\,T}H_F(x)z. Their matrices and inverses, with every fixed derivative, are bounded on the chart closure. The exact adjoint and its derivatives are p*=HE−1p¯THF,∂xα∂ξβp*=∑α1+α2+α3=αα!α1!α2!α3!(∂xα1HE−1)∂xα2∂ξβp¯T(∂xα3HF),∂xα∂ξβG=∑α1+α2=αβ1+β2=βα!β!α1!α2!β1!β2!(∂xα1∂ξβ1p*)(∂xα2∂ξβ2p).(OI1) \begin{aligned} p^*&=H_E^{-1}\overline p^{\,T}H_F,\\ \partial_x^\alpha\partial_\xi^\beta p^* &=\sum_{\alpha_1+\alpha_2+\alpha_3=\alpha} \frac{\alpha!}{\alpha_1!\alpha_2!\alpha_3!} (\partial_x^{\alpha_1}H_E^{-1}) \overline{\partial_x^{\alpha_2}\partial_\xi^\beta p}^{\,T} (\partial_x^{\alpha_3}H_F),\\ \partial_x^\alpha\partial_\xi^\beta G &=\sum_{\substack{\alpha_1+\alpha_2=\alpha\\ \beta_1+\beta_2=\beta}} \frac{\alpha!\beta!}{\alpha_1!\alpha_2!\beta_1!\beta_2!} (\partial_x^{\alpha_1}\partial_\xi^{\beta_1}p^*) (\partial_x^{\alpha_2}\partial_\xi^{\beta_2}p). \end{aligned} \tag{OI1} Thus there are finite constants Cα,βC_{\alpha,\beta}, in the original fiber operator norms, for which ∥∂xα∂ξβG∥≤Cα,β⟨ξ⟩2m−|β|\|\partial_x^\alpha\partial_\xi^\beta G\| \le C_{\alpha,\beta}\langle\xi\rangle^{2m-|\beta|}. The inequality in (OM11) gives ∥G−1∥≤c−2⟨ξ⟩−2m\|G^{-1}\|\le c^{-2}\langle\xi\rangle^{-2m}. For the nonzero combined multiindex κ=(α,β)\kappa=(\alpha,\beta), every derivative of the inverse is the following finite ordered sum: ∂xα∂ξβG−1=∑r=1|α|+|β|(−1)r∑α1+⋯+αr=αβ1+⋯+βr=β|αj|+|βj|>0(1≤j≤r)α!β!α1!⋯αr!β1!⋯βr!G−1(∂xα1∂ξβ1G)G−1⋯(∂xαr∂ξβrG)G−1.(OI2) \partial_x^\alpha\partial_\xi^\beta G^{-1} =\sum_{r=1}^{|\alpha|+|\beta|}(-1)^r \sum_{\substack{\alpha_1+\cdots+\alpha_r=\alpha\\ \beta_1+\cdots+\beta_r=\beta\\ |\alpha_j|+|\beta_j|>0\ (1\le j\le r)}} \frac{\alpha!\beta!} {\alpha_1!\cdots\alpha_r!\beta_1!\cdots\beta_r!} G^{-1}(\partial_x^{\alpha_1}\partial_\xi^{\beta_1}G)G^{-1} \cdots (\partial_x^{\alpha_r}\partial_\xi^{\beta_r}G)G^{-1}. \tag{OI2} To prove the formula, at the point under consideration expand G(x+y,ξ+η)−G(x,ξ)G(x+y,\xi+\eta)-G(x,\xi) in its finite Taylor jet. The coefficients of the inverse jet are uniquely determined by multiplying it with the jet of GG and setting the product equal to IEI_E. The ordered expression G−1−G−1HG−1+G−1HG−1HG−1−⋯G^{-1}-G^{-1}HG^{-1}+G^{-1}HG^{-1}HG^{-1}-\cdots, with H=G(x+y,ξ+η)−G(x,ξ)H=G(x+y,\xi+\eta)-G(x,\xi), gives those coefficients: in derivative degree |α|+|β||\alpha|+|\beta|, only the displayed finite range of rr can contribute. Expanding each factor of HH gives exactly the factorials in (OI2). This proves an identity of derivatives of the actual smooth inverse; it does not require convergence of an infinite series.

In particular, the complete bound is ∥∂xα∂ξβG−1∥≤⟨ξ⟩−2m−|β|∑r=1|α|+|β|∑α1+⋯+αr=αβ1+⋯+βr=β|αj|+|βj|>0(1≤j≤r)α!β!c−2(r+1)α1!⋯αr!β1!⋯βr!∏j=1rCαj,βj.(OI3) \begin{aligned} \|\partial_x^\alpha\partial_\xi^\beta G^{-1}\| &\le\langle\xi\rangle^{-2m-|\beta|} \sum_{r=1}^{|\alpha|+|\beta|} \sum_{\substack{\alpha_1+\cdots+\alpha_r=\alpha\\ \beta_1+\cdots+\beta_r=\beta\\ |\alpha_j|+|\beta_j|>0\ (1\le j\le r)}} \frac{\alpha!\beta!\,c^{-2(r+1)}} {\alpha_1!\cdots\alpha_r!\beta_1!\cdots\beta_r!} \prod_{j=1}^r C_{\alpha_j,\beta_j}. \end{aligned} \tag{OI3} Indeed, the r+1r+1 inverse factors contribute order −2m(r+1)-2m(r+1) and the rr differentiated GG factors contribute order 2mr−|β|2mr-|\beta|. The original mm is retained in both contributions. Finally, ∂xα∂ξβq0=∑α1+α2=αβ1+β2=βα!β!α1!α2!β1!β2!(∂xα1∂ξβ1G−1)(∂xα2∂ξβ2p*)(OI4) \partial_x^\alpha\partial_\xi^\beta q_0 =\sum_{\substack{\alpha_1+\alpha_2=\alpha\\ \beta_1+\beta_2=\beta}} \frac{\alpha!\beta!}{\alpha_1!\alpha_2!\beta_1!\beta_2!} (\partial_x^{\alpha_1}\partial_\xi^{\beta_1}G^{-1}) (\partial_x^{\alpha_2}\partial_\xi^{\beta_2}p^*) \tag{OI4} has order −m−|β|-m-|\beta|. If the scalar cutoff is ϑ\vartheta, then q=ϑG−1p*q=\vartheta G^{-1}p^* on the region where the inverse is defined and is zero below that region; exactly qp−IE=(ϑ−1)IEqp-I_E=(\vartheta-1)I_E. Each derivative of ϑ\vartheta is retained by the product rule. All terms with a derivative of the cutoff, and (ϑ−1)IE(\vartheta-1)I_E, have bounded frequency support on this compact chart and belong to every lower symbol order. For the right construction below, replace GG by pp*pp^*, use (OM3) in the original FF metric, and retain the final order p*(pp*)−1p^*(pp^*)^{-1}. The same finite derivative sums prove every symbol bound in (OM17).

Quantize qq to Q0∈Ψ−m(F,E)Q_0\in\Psi^{-m}(F,E). The full composition formula, including its first derivative correction, gives RE=IE−Q0P∈Ψ−1(E,E),QN=∑j=0N−1REjQ0,QNP=IE−REN.(OM13) R_E=I_E-Q_0P\in\Psi^{-1}(E,E),\qquad Q_N=\sum_{j=0}^{N-1}R_E^jQ_0,\qquad Q_NP=I_E-R_E^N. \tag{OM13} The factor order in QNQ_N is fixed by the exact telescoping identity. The asymptotic-summation theorem chooses Q∈Ψ−m(F,E)Q\in\Psi^{-m}(F,E) whose difference from QNQ_N lies in Ψ−m−N\Psi^{-m-N} for every NN. Multiplying by PP and using REN∈Ψ−NR_E^N\in\Psi^{-N} proves QP=IE−SE,SE∈Ψ−∞(E,E).(OM14) QP=I_E-S_E,\qquad S_E\in\Psi^{-\infty}(E,E). \tag{OM14} Conversely (OM14) gives qp−IE∈S−1qp-I_E\in S^{-1} by taking its principal symbol. If merely q∈S−mq\in S^{-m} and qp−IE∈S−1qp-I_E\in S^{-1}, then for sufficiently large |ξ||\xi|, 12∥w∥≤∥qpw∥≤C⟨ξ⟩−m∥pw∥,(OM15) \tfrac12\|w\|\le\|qpw\| \le C\langle\xi\rangle^{-m}\|pw\|, \tag{OM15} so (OM2) follows. Finally (OM14) implies ∥u∥Hs≤C(∥Pu∥Hs−m+∥SEu∥Hs)\|u\|_{H^s}\le C(\|Pu\|_{H^{s-m}}+\|S_Eu\|_{H^s}). The smoothing operator is compact on HsH^s by the existing finite-rank kernel approximation. If a bounded sequence has convergent PujPu_j, first take a subsequence with convergent SEujS_Eu_j, then (OM14) makes uj=QPuj+SEuju_j=QPu_j+S_Eu_j converge. The compactness characterization of upper semi-Fredholm maps proves finite kernel and closed range for every ss. Its kernel is smooth because Pu=0Pu=0 gives u=SEuu=S_Eu, independently of ss.

Combining Sections 2–4 proves the four equivalent left assertions: finite kernel and closed range at some ss, the same at every ss, (OM12), and (OM14). It also proves the exact estimate (OM5). No finite-cokernel conclusion was inserted.

5. The distinct right condition and the Fredholm consequence

If ran⁡Ps\operatorname{ran}P_s has finite algebraic codimension, it is closed by the finite-codimension bounded-range theorem in the linked Fredholm lesson. Correction of the dual type. With E*,F*E^*,F^* denoting the ordinary complex-linear dual bundles, the following original arrow is the bilinear transpose, denoted Ps*P_s^* in this arrow. Its exact connection to the Hermitian anti-dual is proved below. Ps*:Hm−s(X;F*⊗ΩX1/2)→H−s(X;E*⊗ΩX1/2).(OM16) P_s^*:H^{m-s}(X;F^*\otimes\Omega_X^{1/2}) \longrightarrow H^{-s}(X;E^*\otimes\Omega_X^{1/2}). \tag{OM16} Its kernel is the bilinear annihilator of ran⁡Ps\operatorname{ran}P_s, so it is finite dimensional. Its range is closed: on (ker⁡Ps*)⟂(\ker P_s^*)^\perp, the inverse bound follows from the bounded inverse of PsP_s on (ker⁡Ps)⟂(\ker P_s)^\perp, transported through the exact dual maps below. The left theorem applied to Ps*P_s^* yields (OM3) after the reflected-covector and Hermitian comparisons below. The transpose symbol comes from pp at the reflected covector; the actual Hermitian adjoint symbol has its own metric factors. The following proof retains both maps without identifying EE with FF.

Conversely (OM3) makes pp*:F→Fpp^*:F\to F invertible at high frequency. The right symbol qR=p*(pp*)−1:F→E,pqR=IF,qR∈S−m(OM17) q_R=p^*(pp^*)^{-1}:F\longrightarrow E,\qquad pq_R=I_F,\qquad q_R\in S^{-m} \tag{OM17} has the same exact inverse-derivative proof as (OM11). The right-handed finite sum QR,N=QR,0∑j<NRFjQ_{R,N}=Q_{R,0}\sum_{j<N}R_F^j, with RF=IF−PQR,0∈Ψ−1(F,F)R_F=I_F-PQ_{R,0}\in\Psi^{-1}(F,F), satisfies PQR,N=IF−RFN,PQR=IF−SF,SF∈Ψ−∞(F,F).(OM18) PQ_{R,N}=I_F-R_F^N,\qquad PQ_R=I_F-S_F,\quad S_F\in\Psi^{-\infty}(F,F). \tag{OM18} Taking adjoints and using the left theorem proves that PsP_s has closed range and finite cokernel for every ss. Thus finite-codimension range at some/every order, a right symbol inverse modulo S−1S^{-1}, a right smoothing parametrix, and (OM3) are equivalent. No finite-kernel conclusion was inserted.

The complete dual-bundle comparison

Keep the original Hermitian metrics, half-densities and Sobolev orders. Choose a smooth positive density μ\mu, put ρ=μ1/2\rho=\mu^{1/2}, and use the convention that hE(w,v)h_E(w,v) is linear in ww. For half-density sections define the conjugate-linear bundle isomorphism CE(vρ)=hE(⋅,v)ρ:E⊗Ω1/2→E*⊗Ω1/2,ℬE(u,CEv)=∫XhE(u,v),ℬE(u,ϕ)=∫Xϕ(u).(OD1) C_E(v\rho)=h_E(\,\cdot,v)\rho: E\otimes\Omega^{1/2}\longrightarrow E^*\otimes\Omega^{1/2}, \quad \mathcal B_E(u,C_Ev)=\int_Xh_E(u,v), \quad \mathcal B_E(u,\phi)=\int_X\phi(u). \tag{OD1} The last two integrands are densities: in the chosen presentation they contain the full factor ρ2=μ\rho^2=\mu. The induced dual metric makes CEC_E a fibrewise conjugate-linear isometry; its inverse is smooth. Construct CFC_F in the same way. In a coordinate half-density frame CEv=ME(x)v¯C_Ev=M_E(x)\overline v, and every derivative is Dα(MEv¯)=∑β≤α(αβ)(Dα−βME)(−1)|β|Dβv¯.(OD2) D^\alpha(M_E\overline v) =\sum_{\beta\leq\alpha}\binom{\alpha}{\beta} (D^{\alpha-\beta}M_E)(-1)^{|\beta|} \overline{D^\beta v}. \tag{OD2} The identical formula holds for the inverse matrix. Complex conjugation reflects ξ\xi to −ξ-\xi, preserving the radial Sobolev weight. Smooth multiplication and (OD2) therefore give continuous inverse maps on every original Sobolev order. The full proof of these distribution, metric and density maps is Linear distribution tests and Hermitian adjoints; here we use its half-density form (OD1), with the density still present in the pairing.

Let P†P^\dagger denote the formal Hermitian adjoint and PtP^{\mathrm t} the bilinear transpose. Their defining pairing identities give exactly P†:Hm−s(F⊗Ω1/2)→H−s(E⊗Ω1/2),Pt=CEP†CF−1:Hm−s(F*⊗Ω1/2)→H−s(E*⊗Ω1/2),ℬF(Pu,CFv)=∫XhF(Pu,v)=∫XhE(u,P†v)=ℬE(u,CEP†v).(OD3) \begin{aligned} P^\dagger&:H^{m-s}(F\otimes\Omega^{1/2}) \longrightarrow H^{-s}(E\otimes\Omega^{1/2}),\\ P^{\mathrm t}&=C_E P^\dagger C_F^{-1}: H^{m-s}(F^*\otimes\Omega^{1/2}) \longrightarrow H^{-s}(E^*\otimes\Omega^{1/2}),\\ \mathcal B_F(Pu,C_Fv) &=\int_Xh_F(Pu,v) =\int_Xh_E(u,P^\dagger v) =\mathcal B_E(u,C_E P^\dagger v). \end{aligned} \tag{OD3} Two conjugate-linear maps surrounding the linear adjoint make the transpose linear. For function-section presentations the complete density product is Pμ=μ−1/2Pμ1/2,Pμ†=μ−1/2P†μ1/2,Pt=μ1/2hE♭Pμ†(hF♭)−1μ−1/2,hE♭v=hE(⋅,v).(OD4) P_\mu=\mu^{-1/2}P\mu^{1/2},\qquad P^\dagger_\mu=\mu^{-1/2}P^\dagger\mu^{1/2},\qquad P^{\mathrm t} =\mu^{1/2}h_E^\flat P^\dagger_\mu (h_F^\flat)^{-1}\mu^{-1/2}, \qquad h_E^\flat v=h_E(\,\cdot,v). \tag{OD4} These are exact products. Derivatives of the density and metric in them remain part of the actual operators.

To verify the functional anti-dual as well, let ℛE,s:H−s(E⊗Ω1/2)→(Hs(E⊗Ω1/2))anti\mathcal R_{E,s}:H^{-s}(E\otimes\Omega^{1/2}) \to(H^s(E\otimes\Omega^{1/2}))^{\mathrm{anti}} send vv to the conjugate-linear test functional λv(u)=∫hE(v,u)=ℬE(u,CEv)¯\lambda_v(u)=\int h_E(v,u)=\overline{\mathcal B_E(u,C_Ev)}. Sobolev duality in the linked global-index lesson makes this a continuous linear isomorphism. Let ℐE,s\mathcal I_{E,s} be the Hilbert Riesz isomorphism for the actual HsH^s inner product, and similarly for FF. If Ps′λ=λ∘PsP'_s\lambda=\lambda\circ P_s and Ps,H*P_{s,\mathrm H}^* is the Hilbert adjoint between the original Hilbert spaces, then P†=ℛE,s−1Ps′ℛF,s−m=ℛE,s−1ℐE,sPs,H*ℐF,s−m−1ℛF,s−m.(OD5) P^\dagger=\mathcal R_{E,s}^{-1}P'_s\mathcal R_{F,s-m} =\mathcal R_{E,s}^{-1}\mathcal I_{E,s} P_{s,\mathrm H}^* \mathcal I_{F,s-m}^{-1}\mathcal R_{F,s-m}. \tag{OD5} Indeed evaluation of the first product on uu is λv(Pu)=∫hF(v,Pu)=∫hE(P†v,u)\lambda_v(Pu)=\int h_F(v,Pu)=\int h_E(P^\dagger v,u). The defining Hilbert-adjoint identity proves the second product. This is the exact connection between the functional anti-dual, Hermitian formal adjoint and the ordinary dual-bundle arrow (OM16). No original Sobolev realization is replaced by a different one.

The starred bundle in that Sobolev provider denotes the fibrewise anti-dual. Denote it here by EantiE^{\mathrm{anti}}, keeping E*E^* for the ordinary complex-linear dual in (OM16). The exact maps, with their half-density factors retained, are 𝒥E:E*⊗Ω1/2→Eanti⊗Ω1/2,(𝒥Eϕ)(w)=ϕ(w)¯,𝒜E:E⊗Ω1/2→Eanti⊗Ω1/2,(𝒜Ev)(w)=hE(v,w),𝒜E=𝒥ECE.(OA0) \begin{aligned} \mathcal J_E &:E^*\otimes\Omega^{1/2} \longrightarrow E^{\mathrm{anti}}\otimes\Omega^{1/2}, & (\mathcal J_E\phi)(w)&=\overline{\phi(w)},\\ \mathcal A_E &:E\otimes\Omega^{1/2} \longrightarrow E^{\mathrm{anti}}\otimes\Omega^{1/2}, & (\mathcal A_Ev)(w)&=h_E(v,w),\\ \mathcal A_E&=\mathcal J_E C_E. \end{aligned} \tag{OA0} The first map is conjugate-linear and the second is linear; both are bijections. Their inverses are smooth, and (OD2) with the reciprocal Fourier Sobolev weights proves continuity in both directions at every displayed order. If 𝒮E,s\mathcal S_{E,s} denotes the provider’s integration map from its anti-dual bundle to the functional anti-dual, then ℛE,s=𝒮E,s𝒜E\mathcal R_{E,s}=\mathcal S_{E,s}\mathcal A_E: both sides evaluate uu as ∫hE(v,u)\int h_E(v,u). This proves the exact provider comparison used in (OD5).

In coordinates the inverse in (OD2) is explicitly CE−1ϕ=HE−1ϕ¯=ME−1¯ϕ¯C_E^{-1}\phi=H_E^{-1}\overline\phi =\overline{M_E^{-1}}\,\overline\phi, with ME=HETM_E=H_E^T. The product rule in (OD2) applied to this coefficient matrix therefore retains every inverse-metric derivative and conjugation sign as well.

For a closed range, the bounded inverse from (ker⁡Ps)⟂(\ker P_s)^\perp onto ran⁡Ps\operatorname{ran}P_s transposes to a bounded inverse for the Hilbert adjoint between the corresponding closed complements. Thus its kernel is the range orthogonal complement, and its range is (ker⁡Ps)⟂(\ker P_s)^\perp, hence closed. Equations (OD3) and (OD5) transport both conclusions to the exact displayed spaces: ker⁡Pt=CF(ker⁡P†),ran⁡Pt=CE(ran⁡P†),[ϕ]↦[CE−1ϕ](OD6) \ker P^{\mathrm t}=C_F(\ker P^\dagger),\qquad \operatorname{ran}P^{\mathrm t}=C_E(\operatorname{ran}P^\dagger), \qquad [\phi]\longmapsto[C_E^{-1}\phi] \tag{OD6} is the continuous conjugate-linear quotient isomorphism from the transpose cokernel to the adjoint cokernel. The inverse is induced by CEC_E. The same maps work for range closures before imposing closed range. Finite complex dimensions and closedness are preserved.

Finally choose metric matrices by hE(w,v)=v¯THEwh_E(w,v)=\overline v^{\,T}H_Ew, so ME=HETM_E=H_E^T in (OD2). The original full-symbol calculus gives, in dual coordinate frames, a†(x,ξ)=HE(x)−1p(x,ξ)¯THF(x)+r†(x,ξ),at(x,ξ)=p(x,−ξ)T+rt(x,ξ),r†,rt∈Sm−1.(OD7) \begin{aligned} a^\dagger(x,\xi)&=H_E(x)^{-1}\overline{p(x,\xi)}^{\,T}H_F(x) +r_\dagger(x,\xi),\\ a^{\mathrm t}(x,\xi)&=p(x,-\xi)^T+r_{\mathrm t}(x,\xi), \qquad r_\dagger,r_{\mathrm t}\in S^{m-1}. \end{aligned} \tag{OD7} For the transpose, exchange the two kernel variables in (2π)−n∫ei(x−y)⋅ξa(x,ξ)dξ(2\pi)^{-n}\int e^{i(x-y)\cdot\xi}a(x,\xi)\,d\xi and change the full integration variable to −ξ-\xi. The amplitude is a(y,−ξ)Ta(y,-\xi)^T. The complete amplitude reduction, proved in the linked symbol calculus, supplies every derivative term; its leading term is the second line of (OD7), and its remaining terms are precisely of order at most m−1m-1. For the Hermitian adjoint the same kernel calculation conjugates the matrix and retains both metric factors; all their derivatives and the density derivatives remain in the exact product (OD4) and its lower-order remainder. In particular the leading terms satisfy p(x,−ξ)TCFv=CE(HE−1p(x,−ξ)¯THFv),⟨−ξ⟩=⟨ξ⟩.(OD8) p(x,-\xi)^T C_Fv =C_E\!\left(H_E^{-1}\overline{p(x,-\xi)}^{\,T}H_Fv\right), \qquad \langle-\xi\rangle=\langle\xi\rangle. \tag{OD8} Because the CC maps are fibrewise isometries, a lower bound for the transpose transfers to the Hermitian principal map at −ξ-\xi. Every order-m−1m-1 remainder is bounded by a constant times ⟨ξ⟩m−1\langle\xi\rangle^{m-1}, so increasing the radius preserves at least half of any positive order-mm lower bound. Reflection then gives exactly (OM3). This proves the necessity with the original ordinary-dual arrow retained. The signs are tested by P=iIP=iI, for which P†=−iIP^\dagger=-iI and Pt=iIP^{\mathrm t}=iI, and by P=D=−i∂P=D=-i\partial with constant metrics and coordinate density, for which P†=DP^\dagger=D and Pt=−DP^{\mathrm t}=-D.

Every symbol, metric and density derivative

Work in coordinate half-density frames and the original local bundle frames. Let a(x,ξ)∈S1,0ma(x,\xi)\in S^m_{1,0} be the full local symbol of PP, including the chart and support cutoffs, so a−p∈Sm−1a-p\in S^{m-1}. Retain the inverse Fourier factor. Its kernel is KP(x,y)=(2π)−n∫ei(x−y)⋅ξa(x,ξ)dξ.(OA1) K_P(x,y)=(2\pi)^{-n}\int e^{i(x-y)\cdot\xi}a(x,\xi)\,d\xi. \tag{OA1} This is the exact distributional kernel-symbol correspondence E12. Smooth pieces arising off the coordinate diagonal can be included through their exact reconstructed full symbols; their contributions are in S−∞S^{-\infty} and are retained in the exact remainders below.

The pairing identities yield exact coordinate kernels KPt(x,y)=KP(y,x)T=(2π)−n∫ei(x−y)⋅ξa(y,−ξ)Tdξ,KP†(x,y)=HE(x)−1KP(y,x)¯THF(y)=(2π)−n∫ei(x−y)⋅ξHE(x)−1a(y,ξ)¯THF(y)dξ.(OA2) \begin{aligned} K_{P^{\mathrm t}}(x,y)&=K_P(y,x)^T\\ &=(2\pi)^{-n}\int e^{i(x-y)\cdot\xi}a(y,-\xi)^T\,d\xi,\\ K_{P^\dagger}(x,y)&=H_E(x)^{-1}\overline{K_P(y,x)}^{\,T}H_F(y)\\ &=(2\pi)^{-n}\int e^{i(x-y)\cdot\xi} H_E(x)^{-1}\overline{a(y,\xi)}^{\,T}H_F(y)\,d\xi. \end{aligned} \tag{OA2} To prove the second line, substitute a smooth uu into (OD3) and interchange the two compact test variables; the coefficient of v(y)¯\overline{v(y)} is KP(y,x)¯THF(y)\overline{K_P(y,x)}^TH_F(y), and multiplication by HE(x)−1H_E(x)^{-1} solves for the adjoint. No density coefficient is missing here: coordinate half-density contraction already produces |dx||dx|, while a function-section presentation below retains its separate coefficient dd.

The exact left symbols are the following oscillatory integrals, in the sense of E12 and E22: at(x,ξ)=(2π)−n∬e−iw⋅ηa(x+w,−ξ−η)Tdwdη,a†(x,ξ)=(2π)−nHE(x)−1∬e−iw⋅ηa(x+w,ξ+η)¯THF(x+w)dwdη.(OA3) \begin{aligned} a^{\mathrm t}(x,\xi)&=(2\pi)^{-n}\iint e^{-iw\cdot\eta} a(x+w,-\xi-\eta)^T\,dw\,d\eta,\\ a^\dagger(x,\xi)&=(2\pi)^{-n}H_E(x)^{-1} \iint e^{-iw\cdot\eta} \overline{a(x+w,\xi+\eta)}^{\,T}H_F(x+w)\,dw\,d\eta. \end{aligned} \tag{OA3} Indeed insert y=x+wy=x+w in the inverse formula of E12 and shift the kernel frequency by η\eta. The phase is exactly −w⋅η-w\cdot\eta. Expanding the dependence on ww at zero and integrating by parts in η\eta gives Dxα∂ξα/α!D_x^\alpha\partial_\xi^\alpha/\alpha!, with D=−i∂D=-i\partial. The full E20–E21 remainder theorem in the (1,0)(1,0) class gives, for every positive integer NN, the exact identities at=∑|α|<N1α!∂ξαDxα(a(x,−ξ)T)+rt,N,a†=HE−1∑|α|<N1α!∂ξαDxα(a(x,ξ)¯THF(x))+r†,N,rt,N,r†,N∈S1,0m−N.(OA4) \begin{aligned} a^{\mathrm t} &=\sum_{|\alpha|<N}\frac1{\alpha!} \partial_\xi^\alpha D_x^\alpha(a(x,-\xi)^T)+r_{\mathrm t,N},\\ a^\dagger &=H_E^{-1}\sum_{|\alpha|<N}\frac1{\alpha!} \partial_\xi^\alpha D_x^\alpha (\overline{a(x,\xi)}^{\,T}H_F(x))+r_{\dagger,N},\\ r_{\mathrm t,N},r_{\dagger,N}&\in S^{m-N}_{1,0}. \end{aligned} \tag{OA4} Each remainder is defined as the exact full symbol minus its displayed finite sum. In particular, no infinite series is claimed to converge. Their differentiated estimates are ∥∂xγ∂ξδr*,N∥≤CN,γ,δ⟨ξ⟩m−N−|δ|\|\partial_x^\gamma\partial_\xi^\delta r_{*,N}\|\leq C_{N,\gamma,\delta}\langle\xi\rangle^{m-N-|\delta|} on the original compact chart sets, with the finite-seminorm control furnished by the provider. All support-cutoff and smooth off-diagonal contributions belong to these actual remainders.

The transpose terms can also be written without hiding reflection derivatives: ∂ξαDxα(a(x,−ξ)T)=(−1)|α|(−i)|α|((∂ηα∂xαa)(x,−ξ))T.(OA5) \partial_\xi^\alpha D_x^\alpha(a(x,-\xi)^T) =(-1)^{|\alpha|}(-i)^{|\alpha|} ((\partial_\eta^\alpha\partial_x^\alpha a)(x,-\xi))^T. \tag{OA5} The full Hermitian terms, with every metric derivative, are HE−1∑|α|<N∑β≤α1β!(α−β)!(∂ξαDxβa¯T)(Dxα−βHF).(OA6) H_E^{-1}\sum_{|\alpha|<N}\sum_{\beta\leq\alpha} \frac1{\beta!(\alpha-\beta)!} (\partial_\xi^\alpha D_x^\beta\overline a^{\,T}) (D_x^{\alpha-\beta}H_F). \tag{OA6} Every original matrix product is ordered. The output factor HE−1H_E^{-1} is left multiplication, so there is no input-variable derivative of it in this expression. When differentiating the complete symbol, Leibniz’s rule also retains every derivative of HE−1H_E^{-1}. This distinguishes the actual operator coefficients from derivatives used in its symbol estimates.

For μ=d(x)|dx|\mu=d(x)|dx|, d>0d>0, put r(x)=d(x)1/2r(x)=d(x)^{1/2}. The original function presentations have the exact operators Pμ=Mr−1PMrP_\mu=M_{r^{-1}}PM_r and Pμ†=Mr−1P†MrP^\dagger_\mu=M_{r^{-1}}P^\dagger M_r. Their complete left symbols, again with exact remainder of order m−Nm-N, are aμ=r−1∑|α|<N∂ξαaDxαrα!+rμ,N,aμ†=r−1HE−1∑|α|<N∑β+γ+δ=α(∂ξαDxβa¯T)(DxγHF)(Dxδr)β!γ!δ!+r†μ,N.(OA7) \begin{aligned} a_\mu&=r^{-1}\sum_{|\alpha|<N} \frac{\partial_\xi^\alpha a\,D_x^\alpha r}{\alpha!}+r_{\mu,N},\\ a^\dagger_\mu&=r^{-1}H_E^{-1} \sum_{|\alpha|<N}\sum_{\beta+\gamma+\delta=\alpha} \frac{(\partial_\xi^\alpha D_x^\beta\overline a^{\,T}) (D_x^\gamma H_F)(D_x^\delta r)} {\beta!\gamma!\delta!}+r_{\dagger\mu,N}. \end{aligned} \tag{OA7} The first identity is E21 for right multiplication by rr. For the second, its exact kernel is OA2 multiplied by r(x)−1r(x)^{-1} on the output and r(y)r(y) on the input; expand a¯THFr\overline a^TH_Fr by the full multinomial rule. This proves OA7 directly, including its complete metric and density derivatives. Expanding DδrD^\delta r further means derivatives of the original d1/2d^{1/2}, with no density removed or absorbed into a new symbol.

For a differential operator P=∑αAα(x)DαP=\sum_\alpha A_\alpha(x)D^\alpha, the same computation is finite and exact: Ptϕ=∑α(−D)α(AαTϕ),P†v=HE−1∑αDα(Aα¯THFv),Pμ†v=r−1HE−1∑αDα(Aα¯THFrv).(OA8) \begin{aligned} P^{\mathrm t}\phi&=\sum_\alpha(-D)^\alpha(A_\alpha^T\phi),\\ P^\dagger v&=H_E^{-1}\sum_\alpha D^\alpha(\overline{A_\alpha}^{\,T}H_Fv),\\ P^\dagger_\mu v&=r^{-1}H_E^{-1}\sum_\alpha D^\alpha(\overline{A_\alpha}^{\,T}H_Fr v). \end{aligned} \tag{OA8} Leibniz expansion gives every coefficient, metric, density, and input derivative. The first line follows from Dt=−DD^{\mathrm t}=-D for the bilinear integral; the second follows from D†=DD^\dagger=D for the constant coordinate Hermitian integral and retains the full metric product. These give additional direct sign checks for the symbol calculation.

Finally separate the actual lower-order source contribution a−pa-p without discarding it. For every N≥1N\geq1, rt=(a−p)(x,−ξ)T+∑1≤|α|<N∂ξαDxα(a(x,−ξ)T)α!+rt,N,r†=HE−1(a−p¯THF)+HE−1∑1≤|α|<N∂ξαDxα(a¯THF)α!+r†,N.(OA9) \begin{aligned} r_{\mathrm t}&=(a-p)(x,-\xi)^T +\sum_{1\leq|\alpha|<N}\frac{ \partial_\xi^\alpha D_x^\alpha(a(x,-\xi)^T)}{\alpha!} +r_{\mathrm t,N},\\ r_\dagger&=H_E^{-1}(\overline{a-p}^{\,T}H_F) +H_E^{-1}\sum_{1\leq|\alpha|<N}\frac{ \partial_\xi^\alpha D_x^\alpha(\overline a^{\,T}H_F)}{\alpha!} +r_{\dagger,N}. \end{aligned} \tag{OA9} All terms on each right-hand side have order at most m−1m-1. Hence at=p(x,−ξ)T+rt,a†=HE−1p(x,ξ)¯THF+r†,rt,r†∈Sm−1.(OA10) a^{\mathrm t}=p(x,-\xi)^T+r_{\mathrm t}, \qquad a^\dagger=H_E^{-1}\overline{p(x,\xi)}^{\,T}H_F+r_\dagger, \qquad r_{\mathrm t},r_\dagger\in S^{m-1}. \tag{OA10} These are exactly OD7, now with all lower-order contributions and their controlled remainders displayed. The exact original PP, pp, metrics and density remain in every comparison.

Both sides together say that p:Ex→Fxp:E_x\to F_x is a uniformly invertible high-frequency bundle map. This is equivalent to PsP_s being Fredholm for one, hence every, ss; its index is independent of ss because both kernels of PP and P*P^* are smooth and independent of ss. If pp is polyhomogeneous, the two one-sided high-frequency conditions reduce to injectivity and surjectivity, respectively, of its actual homogeneous principal map on the cosphere: compactness of the cosphere supplies the uniform singular-value bounds, and a lower-order change cannot alter them. For unequal bundle ranks, both sides cannot hold simultaneously.

6. The original mixed-order system and its exact comparison

Now keep every component and weight. Let E=⨁k=1KEk,F=⨁j=1JFj,tk,sj∈ℝ,Pjk∈Ψtk−sj(X;Ek,Fj),(OM19) E=\bigoplus_{k=1}^K E_k,\quad F=\bigoplus_{j=1}^J F_j,\quad t_k,s_j\in\mathbb R,\quad P_{jk}\in\Psi^{\,t_k-s_j}(X;E_k,F_j), \tag{OM19} and give the input and output their original Hilbert direct sums ℋt(E)=⨁k=1KHtk(Ek),ℋs(F)=⨁j=1JHsj(Fj),P:ℋt(E)→ℋs(F).(OM20) \mathcal H_t(E)=\bigoplus_{k=1}^K H^{t_k}(E_k),\qquad \mathcal H_s(F)=\bigoplus_{j=1}^J H^{s_j}(F_j),\qquad P:\mathcal H_t(E)\longrightarrow\mathcal H_s(F). \tag{OM20} Each block is bounded by the exact order tk−sjt_k-s_j, so the finite matrix PP is bounded as displayed. In every block retain a principal representative pjk∈Stk−sjp_{jk}\in S^{t_k-s_j}; no common scalar order is assigned to the raw matrix.

For an exact comparison, use the already-constructed positive-principal order-changing isomorphisms A=diag⁡kJEk−tk:⨁kL2(Ek)→≅ℋt(E),B=diag⁡jJFjsj:ℋs(F)→≅⨁jL2(Fj).(OM21) A=\operatorname{diag}_k J_{E_k}^{-t_k}: \bigoplus_k L^2(E_k)\xrightarrow{\cong}\mathcal H_t(E),\qquad B=\operatorname{diag}_j J_{F_j}^{s_j}: \mathcal H_s(F)\xrightarrow{\cong}\bigoplus_jL^2(F_j). \tag{OM21} The auxiliary T=BPAT=BPA has order zero block by block. Its full original-factor principal map is p̃jk(x,ξ)=⟨ξ⟩sjpjk(x,ξ)⟨ξ⟩−tk,P=B−1TA−1.(OM22) \widetilde p_{jk}(x,\xi) =\langle\xi\rangle^{s_j}p_{jk}(x,\xi) \langle\xi\rangle^{-t_k}, \qquad P=B^{-1}TA^{-1}. \tag{OM22} The equalities in (OM21)–(OM22) are exact operator and principal-symbol comparisons. They preserve the raw PjkP_{jk}, the two distinct weight lists, the bundle types, and every factor. The correction terms from composing full symbols are one order lower in each block.

Applying the proven one-sided results to TT and transporting back gives the mixed left criterion: P:ℋt(E)→ℋs(F) has finite kernel and closed range⇔p̃ has a uniform high-frequency left lower bound⇔∃qkj∈Ssj−tk∑jqkjpjℓ−δkℓIEk∈Stℓ−tk−1⇔∃Qkj∈Ψsj−tk(QP−IE)kℓ∈Ψ−∞.(OM23) \begin{array}{c} P:\mathcal H_t(E)\to\mathcal H_s(F) \text{ has finite kernel and closed range}\\ \Longleftrightarrow \widetilde p\text{ has a uniform high-frequency left lower bound}\\ \Longleftrightarrow \exists\,q_{kj}\in S^{s_j-t_k}\quad \sum_jq_{kj}p_{j\ell}-\delta_{k\ell}I_{E_k} \in S^{t_\ell-t_k-1}\\ \Longleftrightarrow \exists\,Q_{kj}\in\Psi^{s_j-t_k}\quad (QP-I_E)_{k\ell}\in\Psi^{-\infty}. \end{array} \tag{OM23} Here qkj=⟨ξ⟩−tkq̃kj⟨ξ⟩sjq_{kj}=\langle\xi\rangle^{-t_k}\widetilde q_{kj} \langle\xi\rangle^{s_j} is the actual raw left inverse obtained from q̃=(p̃*p̃)−1p̃*\widetilde q=(\widetilde p^*\widetilde p)^{-1}\widetilde p^* at high frequency. Direct multiplication keeps the intermediate jj index and gives ∑jqkjpjℓ=⟨ξ⟩−tk(∑jq̃kjp̃jℓ)⟨ξ⟩tℓ.(OM24) \sum_j q_{kj}p_{j\ell} =\langle\xi\rangle^{-t_k} \Bigl(\sum_j\widetilde q_{kj}\widetilde p_{j\ell}\Bigr) \langle\xi\rangle^{t_\ell}. \tag{OM24} Thus the remainder in the original (k,ℓ)(k,\ell) block has order tℓ−tk−1t_\ell-t_k-1, not an untyped scalar −1-1. The full operator parametrix is Q=AQ̃BQ=A\widetilde Q B; exact composition gives QP−IE=A(Q̃T−IE)A−1QP-I_E=A(\widetilde Q T-I_E)A^{-1}, whose every block is smoothing. This proves both the orders and the factor placement in (OM23).

The distinct mixed right criterion is ran⁡P has finite codimension⇔p̃ has a uniform high-frequency right bound⇔∃qkj∈Ssj−tk∑kpjkqkh−δjhIFj∈Ssh−sj−1⇔∃Qkj∈Ψsj−tk(PQ−IF)jh∈Ψ−∞.(OM25) \begin{array}{c} \operatorname{ran}P\text{ has finite codimension}\\ \Longleftrightarrow \widetilde p\text{ has a uniform high-frequency right bound}\\ \Longleftrightarrow \exists\,q_{kj}\in S^{s_j-t_k}\quad \sum_kp_{jk}q_{kh}-\delta_{jh}I_{F_j} \in S^{s_h-s_j-1}\\ \Longleftrightarrow \exists\,Q_{kj}\in\Psi^{s_j-t_k}\quad (PQ-I_F)_{jh}\in\Psi^{-\infty}. \end{array} \tag{OM25} Its raw symbol is qkj=⟨ξ⟩−tk[p̃*(p̃p̃*)−1]kj⟨ξ⟩sjq_{kj}=\langle\xi\rangle^{-t_k} [\widetilde p^*(\widetilde p\widetilde p^*)^{-1}]_{kj} \langle\xi\rangle^{s_j}, with the matrix product taken before selecting the (k,j)(k,j) entry. The right error is on Fj←FhF_j\leftarrow F_h, so its precise order is sh−sj−1s_h-s_j-1. The operator identity is PQ−IF=B−1(TQ̃−IF)BPQ-I_F=B^{-1}(T\widetilde Q-I_F)B. This proves the one-sided analogues in their full original weighted system, including rectangular total ranks.

7. The two-sided mixed Fredholm criterion and its index

If PP is Fredholm, (OM23) and (OM25) force both uniform high-frequency bounds on p̃\widetilde p. They imply equal total fiber ranks and a square inverse with sup⁡|ξ|≥R∥p̃(x,ξ)−1∥<∞\sup_{|\xi|\ge R}\|\widetilde p(x,\xi)^{-1}\|<\infty, uniformly in xx. Conversely that uniform inverse bound supplies both raw inverse symbols with the precise block orders sj−tks_j-t_k, and the asymptotic series from Section 4 produces one QQ with both smoothing residuals. A cosphere-only statement is available when the weighted component symbols have actual homogeneous principal representatives: their leading square map is invertible on the compact cosphere exactly when its smallest singular value has a positive uniform lower bound, and the lower-order remainder preserves that bound above a larger radius. Conversely a uniform bound for the full symbol forces the homogeneous leading map to be injective on every ray, because a null vector there would make its full image O(|ξ|−1)O(|\xi|^{-1}); equal ranks then make it invertible. A general S1,00S^0_{1,0} symbol need not have such a homogeneous cosphere representative. To see that the two one-sided constructions agree modulo smoothing, write their difference as QL−QR=QL(IF−PQR)+(QLP−IE)QR.(OM26) Q_L-Q_R=Q_L(I_F-PQ_R)+(Q_LP-I_E)Q_R. \tag{OM26} Each term is smoothing with its actual source and target type. Thus P:ℋt(E)→ℋs(F) is Fredholm⇔∃R,c>0∀|ξ|≥R:∥p̃(x,ξ)w∥≥c∥w∥,∥p̃(x,ξ)*v∥≥c∥v∥for all x,w,v.(OM27) \begin{aligned} P:\mathcal H_t(E)\to\mathcal H_s(F)\text{ is Fredholm} \quad\Longleftrightarrow\quad& \exists R,c>0\ \forall |\xi|\ge R: \|\widetilde p(x,\xi)w\|\ge c\|w\|,\\ &\hspace{53mm} \|\widetilde p(x,\xi)^*v\|\ge c\|v\| \quad\text{for all }x,w,v . \end{aligned} \tag{OM27} Equivalently, p̃\widetilde p is square and sup⁡x,|ξ|≥R∥p̃(x,ξ)−1∥<∞\sup_{x,|\xi|\ge R}\|\widetilde p(x,\xi)^{-1}\|<\infty. The same cc may be chosen as the smaller of the two positive constants in (OM23) and (OM25). Mere pointwise invertibility at every large covector does not suffice. On S1S^1 with t=s=0t=s=0, take the scalar Fourier multiplier p(ξ)=1/log⁡(2+ξ2)p(\xi)=1/\log(2+\xi^2). Every derivative of log⁡(2+ξ2)\log(2+\xi^2) of positive order is O(⟨ξ⟩−r)O(\langle\xi\rangle^{-r}) at order rr; repeated quotient differentiation and the positive lower bound on the logarithm give |∂ξrp(ξ)|≤Cr⟨ξ⟩−r|\partial_\xi^r p(\xi)|\le C_r\langle\xi\rangle^{-r}, so p∈S1,00p\in S^0_{1,0}. It is positive and invertible at every ξ\xi, but p(k)→0p(k)\to0 along the normalized Fourier modes eikxe^{ikx}. Every finite Fourier sum is in the range, so the range is dense; positivity makes the multiplier injective. If that range were closed, the bounded inverse theorem on the range would give a fixed lower bound on the images of all unit Fourier modes, contradicting p(k)→0p(k)\to0. Thus the range is nonclosed and the operator is not Fredholm. Its inverse has no uniform high-frequency bound, exactly as (OM27) now requires. The exact comparison (OM21) gives ker⁡P=A(ker⁡T),coker⁡P→B≅coker⁡T,ind⁡P=ind⁡T.(OM28) \ker P=A(\ker T),\quad \operatorname{coker}P\xrightarrow[\ B\ ]{\cong}\operatorname{coker}T, \qquad \operatorname{ind}P=\operatorname{ind}T. \tag{OM28} The positive scalar symbols in AA and BB have index zero, as proved for the actual order-changing maps in the global index lesson. Consequently the analytic index of the original mixed system is exactly the analytic index of T=BPAT=BPA, with all component factors retained. When the weighted component symbols are polyhomogeneous, the global index lesson further identifies this integer with the index of their homogeneous invertible cosphere map. For general S1,00S^0_{1,0} symbols, (OM27) uses the full uniformly invertible high-frequency map; no homogeneous cosphere map or topological index of an absent map is asserted. The comparison does not identify the raw matrix with an order-zero matrix by omission of weights.

8. A separate adapted-space example

The necessity in Sections 3 and 5 concerns the standard Sobolev realization (OM1), and (OM27) concerns the exact weighted direct sums (OM20). It does not prohibit a nonelliptic operator from being Fredholm between a different pair of spaces. On 𝕋2\mathbb T^2, let P=∂xP=\partial_x, and write Fourier coordinates (k,ℓ)∈ℤ2(k,\ell)\in\mathbb Z^2. Its scalar principal map iξxi\xi_x vanishes at every nonzero covector with ξx=0\xi_x=0, so it is not elliptic on standard isotropic Sobolev spaces.

Editorial restoration of the torus Fourier factors. Use periodic coordinates on 𝕋2=(ℝ/2πℤ)2\mathbb T^2=(\mathbb R/2\pi\mathbb Z)^2, with density dxdydx\,dy, and retain f̂(k,ℓ)=1(2π)2∫[0,2π]2e−i(kx+ℓy)f(x,y)dxdy,∥f∥22=(2π)2∑k,ℓ|f̂(k,ℓ)|2.(OM29a) \widehat f(k,\ell)=\frac1{(2\pi)^2}\int_{[0,2\pi]^2} e^{-i(kx+\ell y)}f(x,y)\,dx\,dy, \qquad \|f\|_2^2=(2\pi)^2\sum_{k,\ell}|\widehat f(k,\ell)|^2. \tag{OM29a} The norm of the half-density f|dxdy|1/2f|dx\,dy|^{1/2} is the same displayed integral; no density factor is discarded. Set Y={f∈L2(𝕋2):f̂(0,ℓ)=0 for every ℓ},D={u∈Y:∂xu∈Y},∥u∥D2=∥u∥22+∥∂xu∥22.(OM29) Y=\{f\in L^2(\mathbb T^2):\widehat f(0,\ell)=0 \text{ for every }\ell\},\qquad D=\{u\in Y:\partial_xu\in Y\}, \quad \|u\|_D^2=\|u\|_2^2+\|\partial_xu\|_2^2. \tag{OM29} The Fourier graph norm makes DD complete. The map P:D→YP:D\to Y has the exact inverse P−1f̂(k,ℓ)=f̂(k,ℓ)ik(k≠0),∥P−1f∥D2=(2π)2∑k≠0,ℓ(1+1k2)|f̂(k,ℓ)|2≤2∥f∥22.(OM30) \widehat{P^{-1}f}(k,\ell)=\frac{\widehat f(k,\ell)}{ik} \quad(k\ne0),\qquad \|P^{-1}f\|_D^2 =(2\pi)^2\sum_{k\ne0,\ell}\left(1+\frac1{k^2}\right) |\widehat f(k,\ell)|^2\le2\|f\|_2^2. \tag{OM30} Thus P:D→YP:D\to Y is bijective Fredholm of index zero. These are explicitly adapted spaces. The example illustrates the exact limit of standard-Sobolev necessity without asserting the more specialized constant-strength construction.

The exact map from the standard domain to the graph domain

The graph example has a precise connection to the original standard Sobolev realization. Its periodic completeness and every Fourier Sobolev factor are proved in the compact-cylinder Fourier foundations, equations CF1–CF7; the same proof applies to the present torus. Keep the original coordinates, density, derivative ∂x\partial_x and all missing k=0k=0 modes. Put Z=H1(𝕋2)∩Y,∥u∥Z2=(2π)2∑k≠0,ℓ(1+k2+ℓ2)|û(k,ℓ)|2,I:Z→D,Iu=u.(OG1) Z=H^1(\mathbb T^2)\cap Y,\qquad \|u\|_Z^2=(2\pi)^2 \sum_{k\ne0,\ell}(1+k^2+\ell^2)|\widehat u(k,\ell)|^2, \qquad I:Z\longrightarrow D,\quad Iu=u . \tag{OG1} Both spaces are complete in their displayed norms. The coefficient inequality 1+k2≤1+k2+ℓ21+k^2\leq1+k^2+\ell^2 proves ∥Iu∥D≤∥u∥Z\|Iu\|_D\leq\|u\|_Z. If PZP_Z and PDP_D denote the two realizations of the same original derivative, then the actual maps are PZ=PDI:Z→Y,I=PD−1PZ,ran⁡PZ={f∈Y:(2π)2∑k≠0,ℓ1+k2+ℓ2k2|f̂(k,ℓ)|2<∞}.(OG2) P_Z=P_D I:Z\longrightarrow Y,\qquad I=P_D^{-1}P_Z,\qquad \operatorname{ran}P_Z =\left\{f\in Y:(2\pi)^2 \sum_{k\ne0,\ell}\frac{1+k^2+\ell^2}{k^2} |\widehat f(k,\ell)|^2<\infty\right\}. \tag{OG2} The inverse coefficients remain f̂/(ik)\widehat f/(ik), as in (OM30). Necessity of the displayed range condition follows by taking the coefficients of PZu=fP_Zu=f; sufficiency follows by that same division. The kernel is zero. Finite Fourier sums in YY belong to this range, so its closure is all of YY. They are also dense in DD in the graph norm, by truncating its full weighted coefficient sum.

The range is not closed, since uN(x,y)=ei(x+Ny)2πN2+2,∥uN∥Z=1,∥PZuN∥Y=(N2+2)−1/2→0.(OG3) u_N(x,y)=\frac{e^{i(x+Ny)}}{2\pi\sqrt{N^2+2}},\qquad \|u_N\|_Z=1,\qquad \|P_Zu_N\|_Y=(N^2+2)^{-1/2}\longrightarrow0. \tag{OG3} A closed range would give a bounded inverse from that range to ZZ, contradicting (OG3). The inclusion is proper as well: u*=∑ℓ≥1ℓ−1ei(x+ℓy)u_*=\sum_{\ell\geq1}\ell^{-1}e^{i(x+\ell y)} has graph norm squared (2π)2∑ℓ≥12ℓ−2<∞(2\pi)^2\sum_{\ell\geq1}2\ell^{-2}<\infty, while its ZZ sum is (2π)2∑ℓ≥1(2+ℓ2)ℓ−2=∞(2\pi)^2\sum_{\ell\geq1}(2+\ell^2)\ell^{-2}=\infty. Thus I(Z)I(Z) is a proper dense subspace of DD.

This also constructs the exact object specified by the range defect: 𝔇=D/I(Z),Y/ran⁡PZ→≅𝔇,[f]↦[PD−1f],[u]↦[PDu] for the inverse.(OG4) \mathfrak D=D/I(Z),\qquad Y/\operatorname{ran}P_Z\xrightarrow{\;\cong\;}\mathfrak D,\qquad [f]\longmapsto[P_D^{-1}f],\qquad [u]\longmapsto[P_Du]\ \text{ for the inverse}. \tag{OG4} Well-definedness follows from (OG2), and both composites are the identity. These are linear isomorphisms of the algebraic quotients and continuous inverse maps for their quotient topologies, because PDP_D and its actual inverse are bounded. Both quotient seminorms are zero, since both subspaces being divided out are dense. The quotients are therefore not Hausdorff; their algebraic classes have not been erased.

In fact their algebraic dimension is infinite. Split the positive integers into the disjoint infinite sets Sj={2j−1(2q−1):q≥1}S_j=\{2^{j-1}(2q-1):q\geq1\}, j≥1j\geq1, and put uj=∑ℓ∈Sjℓ−1ei(x+ℓy)u_j=\sum_{\ell\in S_j}\ell^{-1}e^{i(x+\ell y)}. Every uju_j belongs to DD by the full graph sum above. For a finite combination with any nonzero coefficient cjc_j, the ZZ sum over that set is at least (2π)2|cj|2∑ℓ∈Sj1=∞(2\pi)^2|c_j|^2\sum_{\ell\in S_j}1=\infty. Disjointness prevents cancellation. Thus the classes [uj][u_j] are linearly independent in 𝔇\mathfrak D, and their corresponding [PDuj][P_Du_j] are independent in the actual algebraic cokernel.

The full algebraic size of the original defect

Keep the same DD, ZZ, density, Fourier factors, quotient maps, and derivative. For each real α∈(1/2,3/2]\alpha\in(1/2,3/2], define uα=∑ℓ≥1ℓ−αei(x+ℓy).(OG5) u_\alpha=\sum_{\ell\geq1}\ell^{-\alpha}e^{i(x+\ell y)}. \tag{OG5} Its graph norm is exactly ∥uα∥D2=2(2π)2∑ℓ≥1ℓ−2α<∞,PDuα=iuα.(OG6) \|u_\alpha\|_D^2=2(2\pi)^2\sum_{\ell\geq1}\ell^{-2\alpha}<\infty, \qquad P_Du_\alpha=i u_\alpha. \tag{OG6} The convergence follows from 2α>12\alpha>1 and the integral comparison for the positive decreasing summands. Thus the series converges in the original complete graph norm, and its stated derivative is its distributional derivative as proved in (OM29)–(OM30). The endpoint α=3/2\alpha=3/2 is included.

Consider a finite nonzero combination of distinct exponents. After discarding zero coefficients and ordering the remaining ones, write 1/2<α1<⋯<αr≤3/21/2<\alpha_1<\cdots<\alpha_r\leq3/2, with c1≠0c_1\ne0. Its exact coefficient at (1,ℓ)(1,\ell) is ∑j=1rcjuαĵ(1,ℓ)=ℓ−α1(c1+∑j=2rcjℓ−(αj−α1)).(OG7) \widehat{\sum_{j=1}^r c_ju_{\alpha_j}}(1,\ell) =\ell^{-\alpha_1} \left(c_1+\sum_{j=2}^r c_j\ell^{-(\alpha_j-\alpha_1)}\right). \tag{OG7} Every term in the last sum tends to zero, since its exponent difference is strictly positive. Choose LL with ∑j=2r|cj|ℓ−(αj−α1)≤|c1|/2\sum_{j=2}^r|c_j|\ell^{-(\alpha_j-\alpha_1)}\leq|c_1|/2 for every ℓ≥L\ell\geq L. The triangle inequality then gives a coefficient magnitude at least (|c1|/2)ℓ−α1(|c_1|/2)\ell^{-\alpha_1}, without assuming any signs or phases for the complex coefficients. Its original ZZ norm sum is consequently at least (2π)2|c1|24∑ℓ≥L(2+ℓ2)ℓ−2α1≥(2π)2|c1|24∑ℓ≥Lℓ2−2α1=∞.(OG8) \frac{(2\pi)^2|c_1|^2}{4} \sum_{\ell\geq L}(2+\ell^2)\ell^{-2\alpha_1} \geq\frac{(2\pi)^2|c_1|^2}{4} \sum_{\ell\geq L}\ell^{2-2\alpha_1}=\infty. \tag{OG8} Here 2−2α1≥−12-2\alpha_1\geq-1. For −1≤b<0-1\leq b<0, the integral ∫LRxbdx\int_L^R x^b\,dx diverges as R→∞R\to\infty, logarithmically at b=−1b=-1, and comparison proves divergence of the series. For b≥0b\geq0, its summands do not tend to zero. These cover all values in OG8, including the exact upper endpoint. Hence no such combination belongs to ZZ, proving that the classes {[uα]:α∈(1/2,3/2]}in D/I(Z)(OG9) \{[u_\alpha]:\alpha\in(1/2,3/2]\} \quad\text{in }D/I(Z) \tag{OG9} are linearly independent over ℂ\mathbb C. By the original quotient maps (OG4), their classes [PDuα][P_Du_\alpha] are linearly independent in Y/WY/W as well.

The parameter interval has cardinality 𝔠=2ℵ0\mathfrak c=2^{\aleph_0}, so both algebraic quotient dimensions are at least 𝔠\mathfrak c. They are also at most 𝔠\mathfrak c: Fourier coefficients inject DD and YY into ℂℤ2\mathbb C^{\mathbb Z^2}, whose cardinality is (2ℵ0)ℵ0=2ℵ0⋅ℵ0=𝔠(2^{\aleph_0})^{\aleph_0}=2^{\aleph_0\cdot\aleph_0}=\mathfrak c; any quotient has at most the cardinality of its numerator, and a basis is a subset of that quotient. Therefore their exact Hamel dimensions are 𝔠\mathfrak c. This strengthening is solely about the algebraic defect. Both quotient topologies remain exactly the indiscrete topologies proved following (OG4), and the same original graph-domain derivative remains the bounded isomorphism of index zero.

The map PDP_D is still the original bounded graph-domain isomorphism of index zero. Equations (OG1)–(OG4) prove exactly how it is related to the standard-domain operator whose range is dense and nonclosed.

Retaining every mode of the full standard realization

The OG domain retains the no-k=0k=0 condition. For completeness, its relation to the full original standard map PH1:H1(𝕋2)→L2(𝕋2)P_{H^1}:H^1(\mathbb T^2)\to L^2(\mathbb T^2) can be made exact too. Let K1K_1 and K0K_0 consist of the k=0k=0 modes in H1H^1 and L2L^2, respectively. The original full norms give orthogonal decompositions H1=K1⊕Z,L2=K0⊕Y,∥a∥K12=(2π)2∑ℓ(1+ℓ2)|â(0,ℓ)|2.(OG10) H^1=K_1\oplus Z, \qquad L^2=K_0\oplus Y, \qquad \|a\|_{K_1}^2=(2\pi)^2\sum_\ell(1+\ell^2)|\widehat a(0,\ell)|^2. \tag{OG10} The orthogonal projections simply retain or delete the k=0k=0 coefficients and have norm one. The full derivative kills K1K_1 and is PZP_Z on ZZ. Hence ker⁡PH1=K1,ran⁡PH1=W,ran⁡PH1¯L2=Y,L2/W≅K0⊕(Y/W).(OG11) \ker P_{H^1}=K_1, \quad\operatorname{ran}P_{H^1}=W, \quad\overline{\operatorname{ran}P_{H^1}}^{\,L^2}=Y, \quad L^2/W\cong K_0\oplus(Y/W). \tag{OG11} The quotient isomorphism sends [a+f][a+f] to (a,[f])(a,[f]), with inverse (a,[f])↦[a+f](a,[f])\mapsto[a+f]; well-definedness and continuous inverse maps follow from the bounded projections and quotient topology. Similarly H1/K1→ZH^1/K_1\to Z, [a+z]↦z[a+z]\mapsto z, is an isometric quotient isomorphism. Composing it with II and then PDP_D recovers precisely PH1P_{H^1} with its target included from YY into L2L^2. This proves an exact morphism from the full standard realization to the adapted graph-domain realization, including its original infinite nullspace and missing k=0k=0 target modes.

The Hausdorff quotient of the full cokernel is L2/Y≅K0L^2/Y\cong K_0; the remaining dense-range defect is the nonzero algebraic quotient Y/W≅D/I(Z)Y/W\cong D/I(Z) already proved above. These maps retain both the original nullspace and the full target contribution of the zero-frequency direction.

Why a closed graph realization can have a larger domain

Bandara, Goffeng and Saratchandran distinguish a closed operator’s graph domain from the full Sobolev domain obtained under an ellipticity hypothesis; their abstract framework also permits nonelliptic operators. See Realisations of elliptic operators on compact manifolds with boundary, arXiv:2104.01919v2, the Notation discussion of graph norms and closed operators, the Section 2.1 proposition on minimal elliptic domains, and the Appendix B definitions of formally adjointed pairs and their Fredholm property. Here is the exact comparison for our unchanged derivative and spaces.

Regard PD=∂xP_D=\partial_x as a densely defined operator on the original Hilbert space YY, with domain DD. Its smooth core is 𝒞=C∞(𝕋2)∩Y\mathcal C=C^\infty(\mathbb T^2)\cap Y. For u∈Du\in D, the finite Fourier truncations uN=∑0<|k|≤N|ℓ|≤Nû(k,ℓ)ei(kx+ℓy) u_N=\sum_{\substack{0<|k|\le N\\|\ell|\le N}} \widehat u(k,\ell)e^{i(kx+\ell y)} converge in the full graph norm, because ∥u−uN∥D2=(2π)2∑k≠0|k|>Nor|ℓ|>N(1+k2)|û(k,ℓ)|2→0.(OX1) \|u-u_N\|_D^2=(2\pi)^2 \sum_{\substack{k\ne0\\|k|>N\ \mathrm{or}\ |\ell|>N}} (1+k^2)|\widehat u(k,\ell)|^2\longrightarrow0. \tag{OX1} Conversely, a graph limit in Y⊕YY\oplus Y retains ∂xû=ikû\widehat{\partial_xu}=ik\widehat u coefficient by coefficient and therefore belongs to DD. The closure of the derivative on 𝒞\mathcal C and its distributional maximal realization consequently have the same domain DD.

The adjoint on ambient YY has exactly the opposite derivative and the same graph domain: PD*=−PD,dom⁡(PD*)=D.(OX2) P_D^*=-P_D,\qquad\operatorname{dom}(P_D^*)=D. \tag{OX2} Indeed, for u,v∈Du,v\in D, the course’s inner product, linear in its first variable, gives ⟨PDu,v⟩Y=(2π)2∑k≠0,ℓikûv̂¯=(2π)2∑k≠0,ℓû−ikv̂¯=⟨u,−PDv⟩Y. \langle P_Du,v\rangle_Y =(2\pi)^2\sum_{k\ne0,\ell}ik\widehat u\,\overline{\widehat v} =(2\pi)^2\sum_{k\ne0,\ell}\widehat u\, \overline{-ik\widehat v}=\langle u,-P_Dv\rangle_Y. Every sum converges by Cauchy–Schwarz. Conversely an adjoint-domain vector vv has a representative g∈Yg\in Y for this functional. Testing each mode with k≠0k\ne0 forces ĝ=−ikv̂\widehat g=-ik\widehat v; its finite YY norm forces the complete graph sum defining DD. This proves both assertions in (OX2). Conjugating the pairing changes to the source’s inner-product convention and leaves this adjoint unchanged. This star is the adjoint of the unbounded operator on YY; the bounded map D→YD\to Y uses a different domain inner product.

In the source’s terminology the formally adjointed pair is exactly Tmin=PD,Tmin⁡†=−PD,Tmax=(−PD)*=PD,Tmax⁡†=PD*=−PD.(OX3) T_{\min}=P_D,\quad T_{\min}^{\dagger}=-P_D, \quad T_{\max}=(-P_D)^*=P_D, \quad T_{\max}^{\dagger}=P_D^*=-P_D. \tag{OX3} All four domains are DD. Formula (OM30), including its full factor (2π)2(1+k−2)(2\pi)^2(1+k^{-2}), proves that both minimal maps have range YY and zero kernel. Thus this is a Fredholm formally adjointed pair in the source’s definition. Its Cauchy quotient is dom⁡(Tmax)/dom⁡(Tmin)=D/D=0.(OX4) \operatorname{dom}(T_{\max})/ \operatorname{dom}(T_{\min})=D/D=0. \tag{OX4} The range-defect object from (OG4) has the exact comparison map 𝔇=D/I(Z)→D/D,[u]I(Z)↦[u]D=0.(OX5) \mathfrak D=D/I(Z)\longrightarrow D/D, \qquad[u]_{I(Z)}\longmapsto[u]_D=0. \tag{OX5} It is well defined and continuous because it is induced by the identity on DD; its kernel is all of 𝔇\mathfrak D. The infinitely many algebraic classes proved in (OG4) remain present in the source of this map.

The finite truncations in (OX1) also belong to ZZ, so the closure of the graph of PZP_Z in ambient Y⊕YY\oplus Y is the graph of PDP_D. This closure is proper: the original u*u_* above belongs to D\ZD\setminus Z. Hence PZ:Z→YP_Z:Z\to Y is bounded for its specified H1H^1 norm, but the operator with domain ZZ on ambient YY is not closed. It does not contain TminT_{\min}, as the source’s definition of a realization requires.

There is also an exact compactness distinction. The modes wℓ=ei(x+ℓy)2π2(ℓ≥1)(OX6) w_\ell=\frac{e^{i(x+\ell y)}}{2\pi\sqrt2} \quad(\ell\ge1) \tag{OX6} have graph norm one and YY norm 1/21/\sqrt2. Distinct modes have YY-distance one, so D↪YD\hookrightarrow Y is not compact. The derivative’s symbol iξxi\xi_x vanishes at nonzero covectors with ξx=0\xi_x=0; the ellipticity hypothesis used to identify a minimal graph domain with a full Sobolev domain is absent. Equations (OX1)–(OX6) retain the exact domain, adjoint, quotient and compactness information responsible for the different Fredholm conclusions.

The exact circle Fourier provider for the examples

The periodic completeness proof linked above is written on the original two-dimensional torus. Its exact map to the circle used below is ι:L2(𝕋;dx)→L2(𝕋2;dxdy),(ιf)(x,y)=f(x)2π,∥ιf∥22=12π∫02π∫02π|f(x)|2dxdy=∥f∥22.(OC1) \iota:L^2(\mathbb T;dx)\longrightarrow L^2(\mathbb T^2;dx\,dy),\qquad (\iota f)(x,y)=\frac{f(x)}{\sqrt{2\pi}},\qquad \|\iota f\|_2^2=\frac1{2\pi} \int_0^{2\pi}\int_0^{2\pi}|f(x)|^2\,dx\,dy =\|f\|_2^2. \tag{OC1} The original coefficient conventions give exactly f̂(k)=12π∫02πe−ikxf(x)dx,ιf̂(k,ℓ)=δℓ02πf̂(k).(OC2) \widehat f(k)=\frac1{2\pi}\int_0^{2\pi}e^{-ikx}f(x)\,dx, \qquad \widehat{\iota f}(k,\ell) =\frac{\delta_{\ell0}}{\sqrt{2\pi}}\widehat f(k). \tag{OC2} If ff is orthogonal to every eikx/2πe^{ikx}/\sqrt{2\pi}, then (OC2) shows that ιf\iota f is orthogonal to every ei(kx+ℓy)/(2π)e^{i(kx+\ell y)}/(2\pi). The full torus completeness theorem therefore gives ιf=0\iota f=0, hence f=0f=0. This proves circle completeness, and the torus coefficient norm yields the full circle Parseval factor ∥f∥22=2π∑k|f̂(k)|2\|f\|_2^2=2\pi\sum_k|\widehat f(k)|^2. For every original real Sobolev order ss, the same exact coefficient map gives ∥ιf∥Hs(𝕋2)2=(2π)2∑k,ℓ(1+k2+ℓ2)s|δℓ02πf̂(k)|2=2π∑k(1+k2)s|f̂(k)|2=∥f∥Hs(𝕋)2.(OC3) \begin{aligned} \|\iota f\|_{H^s(\mathbb T^2)}^2 &=(2\pi)^2\sum_{k,\ell}(1+k^2+\ell^2)^s \left|\frac{\delta_{\ell0}}{\sqrt{2\pi}}\widehat f(k)\right|^2\\ &=2\pi\sum_k(1+k^2)^s|\widehat f(k)|^2 =\|f\|_{H^s(\mathbb T)}^2. \end{aligned} \tag{OC3} Finite sums are dense in this circle coefficient norm by convergence of the full weighted sum. They also show directly that the original D=−i∂xD=-i\partial_x has coefficient kf̂(k)k\widehat f(k), while J=⟨D⟩J=\langle D\rangle has coefficient (1+k2)1/2f̂(k)(1+k^2)^{1/2}\widehat f(k), at every displayed source and target order below. No circle measure or missing coefficient factor is suppressed.

9. Worked examples

Example 9.1 (left and right are different). On the circle let D=−i∂xD=-i\partial_x, with Fourier eigenvectors ek(x)=eikxe_k(x)=e^{ikx}. For any real ss, define PL:Hs→Hs−1⊕Hs−1,PLu=(Du,0),(OM31) P_L:H^s\longrightarrow H^{s-1}\oplus H^{s-1}, \qquad P_Lu=(Du,0), \tag{OM31} and PR:Hs⊕Hs→Hs−1,PR(v,w)=Dv.(OM32) P_R:H^s\oplus H^s\longrightarrow H^{s-1}, \qquad P_R(v,w)=Dv. \tag{OM32} The first principal map sends z↦(ξz,0)z\mapsto(\xi z,0). For |ξ|≥1|\xi|\ge1, |ξ|≥2−1/2⟨ξ⟩|\xi|\ge2^{-1/2}\langle\xi\rangle, so it satisfies the left bound (OM2). Its kernel is the one-dimensional constant mode. Its range is the mean-zero subspace in the first target component and zero in the second, hence is closed with infinite codimension. The second principal map sends (z1,z2)↦ξz1(z_1,z_2)\mapsto\xi z_1; it satisfies the right bound (OM3). Its range is the mean-zero subspace of Hs−1H^{s-1}, of codimension one, while its kernel consists of the constant first component together with every second-component function and is infinite dimensional. These exact Fourier images show that neither one-sided conclusion can be strengthened to Fredholmness.

Example 9.2 (four distinct component orders). On the circle let J=⟨D⟩J=\langle D\rangle, the positive Fourier multiplier with eigenvalues ⟨k⟩=(1+k2)1/2\langle k\rangle=(1+k^2)^{1/2}. Keep source weights t=(2,0)t=(2,0) and target weights s=(1,−1)s=(1,-1). The full mixed system and its inverse are P=(JJ−1J32J):H2⊕H0→H1⊕H−1,Q=(2J−1−J−3−JJ−1):H1⊕H−1→H2⊕H0.(OM33) P= \begin{pmatrix} J&J^{-1}\\ J^3&2J \end{pmatrix}: H^2\oplus H^0\longrightarrow H^1\oplus H^{-1}, \qquad Q= \begin{pmatrix} 2J^{-1}&-J^{-3}\\ -J&J^{-1} \end{pmatrix}: H^1\oplus H^{-1}\longrightarrow H^2\oplus H^0. \tag{OM33} The four input-to-output orders of PP are 1,−1,3,11,-1,3,1 in row order; those of QQ are −1,−3,1,−1-1,-3,1,-1. With A=diag⁡(J−2,I)A=\operatorname{diag}(J^{-2},I), B=diag⁡(J,J−1)B=\operatorname{diag}(J,J^{-1}), the exact comparison is BPA=(1112),A−1QB−1=(2−1−11).(OM34) BPA=\begin{pmatrix}1&1\\1&2\end{pmatrix}, \qquad A^{-1}QB^{-1} =\begin{pmatrix}2&-1\\-1&1\end{pmatrix}. \tag{OM34} All entries are functions of the same JJ, so they commute in this example; direct ordered matrix multiplication gives QP=IH2⊕H0QP=I_{H^2\oplus H^0} and PQ=IH1⊕H−1PQ=I_{H^1\oplus H^{-1}} exactly. The operator is an isomorphism and has index zero. Formula (OM24) explains why its raw inverse entries have four different component orders.

10. Exercises and complete solutions

Exercise 10.1. For PLP_L and PRP_R in Example 9.1, compute their exact kernels, ranges and cokernels. Decide which principal lower bound each satisfies, keeping the source and target ranks visible.

Solution. If Du=0Du=0, then every nonzero Fourier coefficient kû(k)k\widehat u(k) is zero, so ker⁡PL=ℂe0\ker P_L=\mathbb C e_0. Fourier division by k≠0k\ne0 maps each mean-zero Hs−1H^{s-1} function to an HsH^s primitive, because ⟨k⟩s/|k|≤2⟨k⟩s−1\langle k\rangle^s/|k|\le\sqrt2\langle k\rangle^{s-1} for |k|≥1|k|\ge1. Thus ran⁡PL={(f,0):f̂(0)=0}\operatorname{ran}P_L=\{(f,0):\widehat f(0)=0\}. Its quotient contains the entire second Hs−1H^{s-1} component, so its codimension is infinite. The symbol (ξ,0)T(\xi,0)^T has the left lower bound but its adjoint kills (0,1)T(0,1)^T, so it has no right lower bound. For PRP_R, ker⁡PR=ℂe0⊕Hs\ker P_R=\mathbb C e_0\oplus H^s and ran⁡PR={f:f̂(0)=0}\operatorname{ran}P_R=\{f:\widehat f(0)=0\}, of codimension one. Its symbol (ξ,0)(\xi,0) is surjective for ξ≠0\xi\ne0 with a uniform right inverse, while it kills every (0,z2)(0,z_2) and has no left lower bound.

Exercise 10.2. Multiply both matrices in (OM33) in both orders without suppressing any off-diagonal term, and verify the four weighted orders in (OM23)–(OM25).

Solution. The product PQPQ has diagonal entries 2I−I=I2I-I=I and −I+2I=I-I+2I=I. Its off-diagonal entries are −J−2+J−2=0-J^{-2}+J^{-2}=0 and 2J2−2J2=02J^2-2J^2=0. The product QPQP has diagonal entries 2I−I=I2I-I=I and −I+2I=I-I+2I=I, with off-diagonal entries 2J−2−2J−2=02J^{-2}-2J^{-2}=0 and −J2+J2=0-J^2+J^2=0. The PP entry orders are t1−s1=1t_1-s_1=1, t2−s1=−1t_2-s_1=-1, t1−s2=3t_1-s_2=3, t2−s2=1t_2-s_2=1; the QQ entry orders are s1−t1=−1s_1-t_1=-1, s2−t1=−3s_2-t_1=-3, s1−t2=1s_1-t_2=1, s2−t2=−1s_2-t_2=-1. An error of one symbolic order below QPQP would have block order tℓ−tk−1t_\ell-t_k-1, while the corresponding error below PQPQ would have sh−sj−1s_h-s_j-1. The exact example has both errors zero.

Exercise 10.3. Let R:Hs(S1)→Hs−1(S1)⊕Hs−1(S1)R:H^s(S^1)\to H^{s-1}(S^1)\oplus H^{s-1}(S^1) be the realization of a two-component operator of order zero. Prove that PL+RP_L+R still has finite kernel and closed range and identify its extended index.

Solution. Every order-zero component maps HsH^s into HsH^s. The embedding Hs(S1)↪Hs−1(S1)H^s(S^1)\hookrightarrow H^{s-1}(S^1) is compact, so RR is compact into the displayed target. The compact-perturbation theorem for upper semi-Fredholm maps in the linked Fredholm lesson applies to PLP_L. It preserves closed range, finite-dimensional kernel and the extended index. Example 9.1 gives index 1−∞=−∞1-\infty=-\infty, so PL+RP_L+R has the same extended value. Its individual kernel dimension need not remain one; compact stability preserves the extended difference, not each defect separately.

11. References and onward use

The proofs use the linked Fredholm, Sobolev, Fourier, duality and symbol-calculus lessons at their stated interfaces. The graph-domain comparison uses Lashi Bandara, Magnus Goffeng and Hemanth Saratchandran, Realisations of elliptic operators on compact manifolds with boundary, arXiv:2104.01919v2, Section 2.1 and Appendix B; (OX1)–(OX6) prove every receiving assertion for the original torus derivative. Sections 6–7 keep the original mixed component orders and both separate one-sided conclusions; later index lessons may use them without replacing a rectangular map by a square one.