Equation form expr-007dac77de886d9f
Read as: false formula A at prefix sigma
Means: false formula A at prefix sigma
Normal Modal Logics
Read as: false formula A at prefix sigma
Means: false formula A at prefix sigma
Read as: false formula B at prefix sigma dot n belongs to Delta
Means: false formula B at prefix sigma dot n belongs to Delta
Read as: Gamma is satisfied in model M of Delta
Means: Gamma is satisfied in model M of Delta
Read as: logic S four equals logic K T four
Means: logic S four equals logic K T four
Read as: logic K T five derives axiom B
Means: logic K T five derives axiom B
Read as: formula A is semantically valid
Means: formula A is semantically valid
Read as: logic D equals logic K D
Means: logic D equals logic K D
Read as: world u
Means: world u
Read as: prefix sigma dot n does not belong to the prefix set of Gamma
Means: prefix sigma dot n does not belong to the prefix set of Gamma
Read as: true p at prefix sigma
Means: true p at prefix sigma
Read as: Gamma union the set containing false formula B at prefix sigma
Means: Gamma union the set containing false formula B at prefix sigma
Read as: possibly formula A does not semantically entail necessarily formula A
Means: possibly formula A does not semantically entail necessarily formula A
Read as: prefix sigma prime belongs to the prefix set of Delta
Means: prefix sigma prime belongs to the prefix set of Delta
Read as: false the disjunction of formula B and formula C belongs to Gamma
Means: false the disjunction of formula B and formula C belongs to Gamma
Read as: p
Means: p
Read as: logic K T derives axiom D
Means: logic K T derives axiom D
Read as: prefix sigma belongs to valuation V of p
Means: prefix sigma belongs to valuation V of p
Read as: prefix one point two point one point three
Means: prefix one point two point one point three
Read as: false disjunction rule
Means: false disjunction rule
Read as: with sign S formula A at prefix sigma belongs to Gamma
Means: with sign S formula A at prefix sigma belongs to Gamma
Read as: true the necessity operator with no printed operand at prefix sigma
Means: true the necessity operator with no printed operand at prefix sigma
Read as: n
Means: n
Read as: logic K B five derives axiom four
Means: logic K B five derives axiom four
Read as: Gamma sub zero is the set of formulas B sub one through B sub n, and is a subset of Gamma
Means: Gamma sub zero is the set of formulas B sub one through B sub n, and is a subset of Gamma
Read as: Propositional prefixed tableau rules. Row one, true negation: from true not A at prefix sigma, infer false A at prefix sigma. False negation: from false not A at prefix sigma, infer true A at prefix sigma. Row two, true conjunction: from true A and B at prefix sigma, stack true A and true B at that prefix. False conjunction: from false A and B at prefix sigma, branch to false A or false B at that prefix. Row three, true disjunction: from true A or B at prefix sigma, branch to true A or true B at that prefix. False disjunction: from false A or B at prefix sigma, stack false A and false B at that prefix. Row four, true conditional: from true if A then B at prefix sigma, branch to false A or true B at that prefix. False conditional: from false if A then B at prefix sigma, stack true A and false B at that prefix. End propositional rule table.
Means: Propositional prefixed tableau rules. Row one, true negation: from true not A at prefix sigma, infer false A at prefix sigma. False negation: from false not A at prefix sigma, infer true A at prefix sigma. Row two, true conjunction: from true A and B at prefix sigma, stack true A and true B at that prefix. False conjunction: from false A and B at prefix sigma, branch to false A or false B at that prefix. Row three, true disjunction: from true A or B at prefix sigma, branch to true A or true B at that prefix. False disjunction: from false A or B at prefix sigma, stack false A and false B at that prefix. Row four, true conditional: from true if A then B at prefix sigma, branch to false A or true B at that prefix. False conditional: from false if A then B at prefix sigma, stack true A and false B at that prefix. End propositional rule table.
Read as: formulas B sub one through B sub n semantically entails formula A
Means: formulas B sub one through B sub n semantically entails formula A
Read as: false conjunction rule
Means: false conjunction rule
Read as: logic K
Means: logic K
Read as: Gamma union the set containing false formula B at prefix sigma dot n
Means: Gamma union the set containing false formula B at prefix sigma dot n
Read as: formulas B sub one through B sub n derives formula A
Means: formulas B sub one through B sub n derives formula A
Read as: interpretation f
Means: interpretation f
Read as: true the conditional from necessarily formula A to formula A at prefix one point two
Means: true the conditional from necessarily formula A to formula A at prefix one point two
Read as: true A or false A
Means: true A or false A
Read as: true necessarily formula B at prefix sigma dot n
Means: true necessarily formula B at prefix sigma dot n
Read as: accessibility relation R holds from interpretation f of prefix sigma to interpretation f of prefix sigma dot n
Means: accessibility relation R holds from interpretation f of prefix sigma to interpretation f of prefix sigma dot n
Read as: interpretation f prime
Means: interpretation f prime
Read as: the conditional from the conjunction of necessarily formula A and necessarily formula B to necessarily the conjunction of formula A and formula B is derivable
Means: the conditional from the conjunction of necessarily formula A and necessarily formula B to necessarily the conjunction of formula A and formula B is derivable
Read as: formula B sub n belongs to Gamma
Means: formula B sub n belongs to Gamma
Read as: formula A is false at prefix sigma in model M of Delta
Means: formula A is false at prefix sigma in model M of Delta
Read as: false formula C at prefix sigma
Means: false formula C at prefix sigma
Read as: false the necessity operator with no printed operand at prefix sigma dot n
Means: false the necessity operator with no printed operand at prefix sigma dot n
Read as: false the necessity operator with no printed operand at prefix sigma
Means: false the necessity operator with no printed operand at prefix sigma
Read as: false possibility rule
Means: false possibility rule
Read as: i equals one
Means: i equals one
Read as: formula B sub i is true at world w in model M
Means: formula B sub i is true at world w in model M
Read as: logic S five derives axiom five
Means: logic S five derives axiom five
Read as: true conditional rule
Means: true conditional rule
Read as: formula B is true at prefix sigma in model M of Delta
Means: formula B is true at prefix sigma in model M of Delta
Read as: formula B is true at interpretation f of prefix sigma in model M
Means: formula B is true at interpretation f of prefix sigma in model M
Read as: true necessarily the disjunction of p and q at prefix one
Means: true necessarily the disjunction of p and q at prefix one
Read as: world set W is the set containing one, one point one, and one point two
Means: world set W is the set containing one, one point one, and one point two
Read as: true A at prefix sigma and false A at prefix sigma
Means: true A at prefix sigma and false A at prefix sigma
Read as: structure M
Means: structure M
Read as: necessarily formula B is true at interpretation f of prefix sigma dot n in model M
Means: necessarily formula B is true at interpretation f of prefix sigma dot n in model M
Read as: false the conditional from formula B to formula C at prefix sigma belongs to Gamma
Means: false the conditional from formula B to formula C at prefix sigma belongs to Gamma
Read as: true the disjunction of formula B and formula C at prefix sigma belongs to Gamma
Means: true the disjunction of formula B and formula C at prefix sigma belongs to Gamma
Read as: true the necessity operator with no printed operand at prefix sigma dot n
Means: true the necessity operator with no printed operand at prefix sigma dot n
Read as: formula A is false at interpretation f of prefix sigma in model M
Means: formula A is false at interpretation f of prefix sigma in model M
Read as: Gamma does not semantically entail formula A
Means: Gamma does not semantically entail formula A
Read as: accessibility relation R holds from interpretation f of prefix sigma dot n to world w
Means: accessibility relation R holds from interpretation f of prefix sigma dot n to world w
Read as: valuation V of q is the singleton containing one point one
Means: valuation V of q is the singleton containing one point one
Read as: true q at prefix one point one
Means: true q at prefix one point one
Read as: true disjunction rule
Means: true disjunction rule
Read as: logic B equals logic K T B
Means: logic B equals logic K T B
Read as: false negation rule
Means: false negation rule
Read as: the conditional from the disjunction of necessarily p and necessarily q to necessarily the disjunction of p and q
Means: the conditional from the disjunction of necessarily p and necessarily q to necessarily the disjunction of p and q
Read as: false formula A at prefix sigma dot n
Means: false formula A at prefix sigma dot n
Read as: world w
Means: world w
Read as: the possibility operator
Means: the possibility operator
Read as: model M and interpretation f prime
Means: model M and interpretation f prime
Read as: true possibly formula B at prefix sigma
Means: true possibly formula B at prefix sigma
Read as: the conditional from possibly the disjunction of formula A and formula B to the disjunction of possibly formula A and possibly formula B is derivable
Means: the conditional from possibly the disjunction of formula A and formula B to the disjunction of possibly formula A and possibly formula B is derivable
Read as: the prefix set of Gamma
Means: the prefix set of Gamma
Read as: logic K D B four derives axiom T
Means: logic K D B four derives axiom T
Read as: the source expression A, without a formula marker, is not semantically valid
Means: the source expression A, without a formula marker, is not semantically valid
Read as: false necessity rule
Means: false necessity rule
Read as: possibly formula B is true at interpretation f of prefix sigma in model M
Means: possibly formula B is true at interpretation f of prefix sigma in model M
Read as: formula B is false at prefix sigma dot n in model M of Delta
Means: formula B is false at prefix sigma dot n in model M of Delta
Read as: formula B is false at interpretation f prime of prefix sigma dot n in model M
Means: formula B is false at interpretation f prime of prefix sigma dot n in model M
Read as: Gamma
Means: Gamma
Read as: the derivability symbol
Means: the derivability symbol
Read as: necessarily formula B is true at the source location f of sigma, followed outside the function argument by dot n, in model M
Means: necessarily formula B is true at the source location f of sigma, followed outside the function argument by dot n, in model M
Read as: true B sub one through true B sub n at prefix one, followed by false A at prefix one
Means: true B sub one through true B sub n at prefix one, followed by false A at prefix one
Read as: logic S five equals logic K T four B
Means: logic S five equals logic K T four B
Read as: true sign
Means: true sign
Read as: prefix set P
Means: prefix set P
Read as: false conditional rule
Means: false conditional rule
Read as: true possibly formula B at prefix sigma
Means: true possibly formula B at prefix sigma
Read as: formula B is true at interpretation f of prefix sigma dot n in model M
Means: formula B is true at interpretation f of prefix sigma dot n in model M
Read as: Gamma is a subset of Delta
Means: Gamma is a subset of Delta
Read as: with sign S formula A at prefix sigma
Means: with sign S formula A at prefix sigma
Read as: true necessarily formula B at prefix sigma
Means: true necessarily formula B at prefix sigma
Read as: logic K four
Means: logic K four
Read as: prefix m
Means: prefix m
Read as: accessibility relation R holds from interpretation f of prefix sigma dot n to interpretation f of prefix sigma
Means: accessibility relation R holds from interpretation f of prefix sigma dot n to interpretation f of prefix sigma
Read as: true the induction formula at prefix sigma belongs to Delta
Means: true the induction formula at prefix sigma belongs to Delta
Read as: prefix sigma is accessible to prefix sigma prime if and only if sigma prime equals sigma dot n for some n
Means: prefix sigma is accessible to prefix sigma prime if and only if sigma prime equals sigma dot n for some n
Read as: prefix sigma dot n belongs to the prefix set of Gamma
Means: prefix sigma dot n belongs to the prefix set of Gamma
Read as: prefix one
Means: prefix one
Read as: model M of Delta is the ordered triple consisting of the prefix set P of Delta, accessibility relation R, and valuation V
Means: model M of Delta is the ordered triple consisting of the prefix set P of Delta, accessibility relation R, and valuation V
Read as: logic K B four derives axiom five
Means: logic K B four derives axiom five
Read as: accessibility relation R holds from interpretation f of prefix sigma to interpretation f of prefix sigma
Means: accessibility relation R holds from interpretation f of prefix sigma to interpretation f of prefix sigma
Read as: if possibly p, then possibly the disjunction of p and q
Means: if possibly p, then possibly the disjunction of p and q
Read as: prefix one point two
Means: prefix one point two
Read as: interpretation f prime of prefix sigma equals interpretation f of prefix sigma
Means: interpretation f prime of prefix sigma equals interpretation f of prefix sigma
Read as: necessarily formula A does not semantically entail possibly formula A
Means: necessarily formula A does not semantically entail possibly formula A
Read as: Gamma is satisfied with respect to interpretation f in model M
Means: Gamma is satisfied with respect to interpretation f in model M
Read as: the prefix set of Delta
Means: the prefix set of Delta
Read as: formula B is true at world w in model M
Means: formula B is true at world w in model M
Read as: false formula B at prefix sigma belongs to Delta
Means: false formula B at prefix sigma belongs to Delta
Read as: true not formula B at prefix sigma belongs to Gamma
Means: true not formula B at prefix sigma belongs to Gamma
Read as: true the conjunction of formula B and formula C
Means: true the conjunction of formula B and formula C
Read as: false necessarily formula A at prefix sigma
Means: false necessarily formula A at prefix sigma
Read as: accessibility relation R contains the ordered pair one to one point one and the ordered pair one to one point two
Means: accessibility relation R contains the ordered pair one to one point one and the ordered pair one to one point two
Read as: the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q is not derivable
Means: the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q is not derivable
Read as: formula A
Means: formula A
Read as: false possibly formula A at prefix sigma
Means: false possibly formula A at prefix sigma
Read as: true formula C at prefix sigma
Means: true formula C at prefix sigma
Read as: accessibility relation R holds from prefix sigma to prefix sigma prime
Means: accessibility relation R holds from prefix sigma to prefix sigma prime
Read as: true negation rule
Means: true negation rule
Read as: necessarily formula B is false at interpretation f of prefix sigma in model M
Means: necessarily formula B is false at interpretation f of prefix sigma in model M
Read as: if possibly formula A, then necessarily possibly formula A
Means: if possibly formula A, then necessarily possibly formula A
Read as: interpretation f prime of prefix sigma dot n equals world w
Means: interpretation f prime of prefix sigma dot n equals world w
Read as: accessibility relation R holds from interpretation f prime of prefix sigma to interpretation f prime of prefix sigma dot n
Means: accessibility relation R holds from interpretation f prime of prefix sigma to interpretation f prime of prefix sigma dot n
Read as: false not formula B at prefix sigma belongs to Gamma
Means: false not formula B at prefix sigma belongs to Gamma
Read as: prefix sigma equals prefix one point two point one
Means: prefix sigma equals prefix one point two point one
Read as: formula A is true at interpretation f of prefix sigma in model M
Means: formula A is true at interpretation f of prefix sigma in model M
Read as: accessibility relation R
Means: accessibility relation R
Read as: logic T equals logic K T
Means: logic T equals logic K T
Read as: true necessity rule
Means: true necessity rule
Read as: interpretation f is a function from prefix set P to world set W
Means: interpretation f is a function from prefix set P to world set W
Read as: true formula A at prefix sigma dot n
Means: true formula A at prefix sigma dot n
Read as: formula C is true at interpretation f of prefix sigma in model M
Means: formula C is true at interpretation f of prefix sigma in model M
Read as: false formula A at prefix sigma belongs to Delta
Means: false formula A at prefix sigma belongs to Delta
Read as: false formula B at prefix sigma
Means: false formula B at prefix sigma
Read as: formula B is false at prefix sigma in model M of Delta
Means: formula B is false at prefix sigma in model M of Delta
Read as: formula C is true at prefix sigma in model M of Delta
Means: formula C is true at prefix sigma in model M of Delta
Read as: prefix sigma
Means: prefix sigma
Read as: true formula A at prefix sigma
Means: true formula A at prefix sigma
Read as: the conditional from formula B to formula C is false at interpretation f of prefix sigma in model M
Means: the conditional from formula B to formula C is false at interpretation f of prefix sigma in model M
Read as: true formula B at prefix sigma belongs to Delta
Means: true formula B at prefix sigma belongs to Delta
Read as: the empty sequence
Means: the empty sequence
Read as: accessibility relation R holds from prefix sigma to prefix sigma dot n
Means: accessibility relation R holds from prefix sigma to prefix sigma dot n
Read as: true necessarily formula B at prefix sigma belongs to Gamma
Means: true necessarily formula B at prefix sigma belongs to Gamma
Read as: true necessarily formula B at prefix sigma dot n
Means: true necessarily formula B at prefix sigma dot n
Read as: formula A is true at prefix sigma in model M of Delta
Means: formula A is true at prefix sigma in model M of Delta
Read as: false formula C at prefix sigma belongs to Delta
Means: false formula C at prefix sigma belongs to Delta
Read as: prefix sigma concatenated with the one-element sequence n
Means: prefix sigma concatenated with the one-element sequence n
Read as: prefix sigma dot three
Means: prefix sigma dot three
Read as: true B sub one through true B sub n at prefix one, followed by false A at prefix one
Means: true B sub one through true B sub n at prefix one, followed by false A at prefix one
Read as: interpretation f of prefix one equals world w
Means: interpretation f of prefix one equals world w
Read as: Gamma semantically entails formula A
Means: Gamma semantically entails formula A
Read as: formula B is false at interpretation f of prefix sigma in model M
Means: formula B is false at interpretation f of prefix sigma in model M
Read as: prefix one point one
Means: prefix one point one
Read as: not formula B is true at interpretation f of prefix sigma in model M
Means: not formula B is true at interpretation f of prefix sigma in model M
Read as: necessarily formula B is true at interpretation f of prefix sigma in model M
Means: necessarily formula B is true at interpretation f of prefix sigma in model M
Read as: false possibly formula B at prefix sigma belongs to Gamma
Means: false possibly formula B at prefix sigma belongs to Gamma
Read as: false the conjunction of formula B and formula C at prefix sigma belongs to Gamma
Means: false the conjunction of formula B and formula C at prefix sigma belongs to Gamma
Read as: formula A is true at world w in model M
Means: formula A is true at world w in model M
Read as: true formula A at prefix sigma belongs to Delta
Means: true formula A at prefix sigma belongs to Delta
Read as: prefix sigma prime
Means: prefix sigma prime
Read as: the set containing false A and true B sub one through true B sub n
Means: the set containing false A and true B sub one through true B sub n
Read as: model M and interpretation f
Means: model M and interpretation f
Read as: Gamma is satisfied with respect to interpretation f in model M
Means: Gamma is satisfied with respect to interpretation f in model M
Read as: true necessarily formula B at prefix sigma dot n belongs to Gamma
Means: true necessarily formula B at prefix sigma dot n belongs to Gamma
Read as: accessibility relation R holds from interpretation f of prefix sigma to world w
Means: accessibility relation R holds from interpretation f of prefix sigma to world w
Read as: the conjunction of formula A and formula B
Means: the conjunction of formula A and formula B
Read as: true formula B at prefix sigma dot n belongs to Delta
Means: true formula B at prefix sigma dot n belongs to Delta
Read as: true formula B at prefix sigma dot n
Means: true formula B at prefix sigma dot n
Read as: prefix set P is a subset of the set of nonempty finite sequences of positive integers
Means: prefix set P is a subset of the set of nonempty finite sequences of positive integers
Read as: true possibility rule
Means: true possibility rule
Read as: false formula A
Means: false formula A
Read as: formula A is derivable
Means: formula A is derivable
Read as: true necessarily formula A at prefix sigma
Means: true necessarily formula A at prefix sigma
Read as: true the conjunction of formula B and formula C at prefix sigma belongs to Gamma
Means: true the conjunction of formula B and formula C at prefix sigma belongs to Gamma
Read as: valuation V of p is the singleton containing one point two
Means: valuation V of p is the singleton containing one point two
Read as: formula C is false at interpretation f of prefix sigma in model M
Means: formula C is false at interpretation f of prefix sigma in model M
Read as: Gamma derives formula A
Means: Gamma derives formula A
Read as: true p at prefix one point two
Means: true p at prefix one point two
Read as: source period
Means: source period
Read as: the conjunction of formula B and formula C is false at interpretation f of prefix sigma in model M
Means: the conjunction of formula B and formula C is false at interpretation f of prefix sigma in model M
Read as: source comma
Means: source comma
Read as: formula B
Means: formula B
Read as: prefix sigma does not belong to valuation V of p
Means: prefix sigma does not belong to valuation V of p
Read as: model M
Means: model M
Read as: formula A is false at world w in model M
Means: formula A is false at world w in model M
Read as: formula B is false at world w in model M
Means: formula B is false at world w in model M
Read as: world w belongs to world set W
Means: world w belongs to world set W
Read as: false necessarily formula B at prefix sigma belongs to Gamma
Means: false necessarily formula B at prefix sigma belongs to Gamma
Read as: the induction formula is true at prefix sigma in model M of Delta
Means: the induction formula is true at prefix sigma in model M of Delta
Read as: true formula A
Means: true formula A
Read as: prefix two
Means: prefix two
Read as: true formula C at prefix sigma belongs to Delta
Means: true formula C at prefix sigma belongs to Delta
Read as: formula B is false at prefix sigma prime in model M of Delta
Means: formula B is false at prefix sigma prime in model M of Delta
Read as: if necessarily formula A, then necessarily possibly formula A
Means: if necessarily formula A, then necessarily possibly formula A
Read as: false possibly formula B at prefix sigma dot n belongs to Gamma
Means: false possibly formula B at prefix sigma dot n belongs to Gamma
Read as: prefix sigma dot n
Means: prefix sigma dot n
Read as: prefix sigma prime belongs to the prefix set of Gamma
Means: prefix sigma prime belongs to the prefix set of Gamma
Read as: Delta is the set containing false A at prefix one and true B sub one through true B sub n at prefix one
Means: Delta is the set containing false A at prefix one and true B sub one through true B sub n at prefix one
Read as: true the induction formula at prefix sigma does not belong to Delta
Means: true the induction formula at prefix sigma does not belong to Delta
Read as: Gamma is satisfied with respect to interpretation f prime in model M
Means: Gamma is satisfied with respect to interpretation f prime in model M
Read as: V
Means: V
Read as: if necessarily the disjunction of p and q, then the disjunction of necessarily p and necessarily q
Means: if necessarily the disjunction of p and q, then the disjunction of necessarily p and necessarily q
Read as: false the induction formula at prefix sigma belongs to Delta
Means: false the induction formula at prefix sigma belongs to Delta
Read as: true the disjunction of formula B and formula C at prefix sigma
Means: true the disjunction of formula B and formula C at prefix sigma
Read as: formula B is true at prefix sigma prime in model M of Delta
Means: formula B is true at prefix sigma prime in model M of Delta
Read as: interpretation f of prefix sigma prime equals interpretation f prime of prefix sigma prime
Means: interpretation f of prefix sigma prime equals interpretation f prime of prefix sigma prime
Read as: prefix sigma belongs to the set of nonempty finite sequences of positive integers
Means: prefix sigma belongs to the set of nonempty finite sequences of positive integers
Read as: true necessarily formula B at prefix sigma
Means: true necessarily formula B at prefix sigma
Read as: the induction formula is false at prefix sigma in model M of Delta
Means: the induction formula is false at prefix sigma in model M of Delta
Read as: true formula B at prefix sigma
Means: true formula B at prefix sigma
Read as: the necessity operator
Means: the necessity operator
Read as: if necessarily the conjunction of p and q, then necessarily p
Means: if necessarily the conjunction of p and q, then necessarily p
Read as: Delta
Means: Delta
Read as: if necessarily not p, then necessarily the conditional from p to q
Means: if necessarily not p, then necessarily the conditional from p to q
Read as: true possibly formula A at prefix sigma
Means: true possibly formula A at prefix sigma
Read as: formula A is not semantically valid
Means: formula A is not semantically valid
Read as: logic K T five derives axiom four
Means: logic K T five derives axiom four
Read as: false sign
Means: false sign
Read as: true conjunction rule
Means: true conjunction rule
Read as: the conjunction of formula B and formula C is true at interpretation f of prefix sigma in model M
Means: the conjunction of formula B and formula C is true at interpretation f of prefix sigma in model M
Read as: the prefix set of Gamma union the set containing prefix sigma dot n
Means: the prefix set of Gamma union the set containing prefix sigma dot n
Read as: true the conditional from formula B to formula C at prefix sigma belongs to Gamma
Means: true the conditional from formula B to formula C at prefix sigma belongs to Gamma
Read as: formula B sub one
Means: formula B sub one
Read as: valuation V of p is the set of prefixes sigma such that true p at prefix sigma belongs to Delta
Means: valuation V of p is the set of prefixes sigma such that true p at prefix sigma belongs to Delta
Four source rows pair the true and false rules for negation, conjunction, disjunction, and the conditional. Branching and stacked conclusions are retained exactly.
From true not A at prefix sigma, infer false A at prefix sigma.
From false not A at prefix sigma, infer true A at prefix sigma.
From true A and B at prefix sigma, stack true A and true B at the same prefix.
From false A and B at prefix sigma, branch to false A or false B at the same prefix.
From true A or B at prefix sigma, branch to true A or true B at the same prefix.
From false A or B at prefix sigma, stack false A and false B at the same prefix.
From true if A then B at prefix sigma, branch to false A or true B at the same prefix.
From false if A then B at prefix sigma, stack true A and false B at the same prefix.
The source table wraps the inner two-column tabular. Listener authority belongs to that inner table so the four rules and used-or-new side conditions are not duplicated.
Two necessity rules and two possibility rules distinguish conclusions at used prefixes from conclusions at new prefixes.
From true necessarily A at prefix sigma, infer true A at prefix sigma dot n, where sigma dot n is used.
From false necessarily A at prefix sigma, infer false A at a new prefix sigma dot n.
From true possibly A at prefix sigma, infer true A at a new prefix sigma dot n.
From false possibly A at prefix sigma, infer false A at prefix sigma dot n, where sigma dot n is used.
A four-node linear tableau closes true necessarily A against false possibly A at prefix one by producing true and false A at prefix one point one.
A four-node linear tableau closes true possibly A against false necessarily A at prefix one by producing true and false A at prefix one point one.
The example gives the two-branch closed tableau deriving that necessarily A and necessarily B implies necessarily A and B.
The tableau expands the negated conditional, creates a new prefix, branches on false A and B, and closes each branch against the corresponding boxed premise.
The example gives the two-branch closed tableau deriving that possibly A or B implies possibly A or possibly B.
The tableau expands the negated conditional, creates one successor, branches on true A or B, and closes both branches against their false possibility premises.
Find closed tableaux for the four printed modal formulas. The source supplies no solutions; the exercise remains unsolved.
An interpretation maps a set of nonempty positive-integer prefixes into model worlds and preserves each printed parent-to-child accessibility relation; truth and falsity of signed formulas are then defined through that map.
A model satisfies Gamma with respect to an interpretation when it satisfies every prefixed formula in Gamma; Gamma is satisfiable when such a model and interpretation exist.
If Gamma contains true A and false A at the same prefix, then Gamma is unsatisfiable.
If Gamma has a closed tableau, then Gamma is unsatisfiable.
Complete the preceding soundness proof. The source does not supply the omitted cases, so the exercise remains unsolved.
If Gamma derives A by the tableau system, then Gamma semantically entails A.
If A is derivable, then A is true in every model.
The source table wraps the inner listener table containing ten T, D, B, four, and four-r rules.
Five paired rows give the necessity and possibility forms of the reflexive, serial, symmetric, transitive, and euclidean-reverse rules, including the printed used-prefix condition.
Rule T necessity: from true necessarily A at prefix sigma, infer true A at prefix sigma.
Rule T possibility: from false possibly A at prefix sigma, infer false A at prefix sigma.
Rule D necessity: from true necessarily A at prefix sigma, infer true possibly A at prefix sigma.
Rule D possibility: from false possibly A at prefix sigma, infer false necessarily A at prefix sigma.
Rule B necessity: from true necessarily A at prefix sigma dot n, infer true A at prefix sigma.
Rule B possibility: from false possibly A at prefix sigma dot n, infer false A at prefix sigma.
Rule four necessity: from true necessarily A at prefix sigma, infer true necessarily A at used prefix sigma dot n.
Rule four possibility: from false possibly A at prefix sigma, infer false possibly A at used prefix sigma dot n.
Rule four r necessity: from true necessarily A at prefix sigma dot n, infer true necessarily A at prefix sigma.
Rule four r possibility: from false possibly A at prefix sigma dot n, infer false possibly A at prefix sigma.
The source table wraps the inner three-column table. Listener authority belongs only to the inner tabular.
Six source rows associate T, D, K four, B, S four, and S five with their printed relation properties and rule families.
The example proves necessarily A implies necessarily possibly A using the ordinary K rules and the four-r possibility rule, ending in a closure at prefix one point one.
A seven-node linear tableau applies false conditional, false necessity, four-r possibility, false possibility, and true necessity rules, then closes on A at prefix one point one.
Construct closed tableaux for the six displayed derivability claims. No tableaux are supplied; the exercise remains unsolved.
The T necessity and T possibility rules are sound for reflexive models.
Complete the proof of soundness for the selected T rule cases. The omitted work remains unsolved.
The D necessity and D possibility rules are sound for serial models.
Complete the proof of soundness for the selected D rule cases. The omitted work remains unsolved.
The B necessity and B possibility rules are sound for symmetric models.
Complete the proof of soundness for the selected B rule cases. The omitted work remains unsolved.
The four necessity and four possibility rules are sound for transitive models.
Complete the proof of soundness for the selected four-rule cases. The omitted work remains unsolved.
The four-r necessity and four-r possibility rules are sound for euclidean models.
Complete the proof of soundness for the selected four-r rule cases. The omitted work remains unsolved.
The tableau systems in the logic-and-rule table are sound for their respective classes of models.
The outer table wraps the inner listener table; its four rules are not repeated as a second listener structure.
Four rules use arbitrary used or new prefixes m rather than prefix extensions sigma dot n.
From true necessarily A at prefix n, infer true A at any used prefix m.
From false necessarily A at prefix n, infer false A at a new prefix m.
From true possibly A at prefix n, infer true A at a new prefix m.
From false possibly A at prefix n, infer false A at any used prefix m.
A six-node linear tableau derives possibly A implies necessarily possibly A and closes on A at prefix three.
The tableau uses prefixes one, two, and three, applies false conditional, false necessity, true possibility, and false possibility, and closes at prefix three.
A branch is complete when every applicable propositional or modal rule has the required printed conclusions, including every used-prefix conclusion and at least one new-prefix conclusion.
Every finite Gamma has a tableau in which every branch is complete.
If Gamma has no closed tableau, then Gamma is satisfiable.
Complete the proof of the preceding completeness theorem. The omitted proof remains unsolved.
If Gamma semantically entails A, then Gamma derives A.
If A is true in every model, then A is derivable.
The example expands a nonderivable formula through three tableau stages, identifies one open complete branch, and reads a three-world countermodel from it.
Seven linear nodes expand the failed box-distribution formula and introduce prefixes one point one and one point two. The source explicitly says the tableau is unfinished.
Nine linear nodes additionally apply true necessity at both used prefixes. The source continues the construction, so this tableau is unfinished.
The third tableau branches three ways: two branches close and the middle branch remains open and complete, supplying the countermodel valuation.
The figure contains the source graph with three worlds, six printed p-and-q valuations, and two directed accessibility edges.
World one points to worlds one point one and one point two. The graph prints both p and q at every world and no other edge or valuation.
the proposition that every finite Gamma has a complete tableau
Read as: true necessarily formula A at prefix sigma
Read as: true necessity rule
Read as: true formula A at prefix sigma dot n
Read as: false necessarily formula A at prefix sigma
Read as: false necessity rule
Read as: false formula A at prefix sigma dot n
Read as: true possibly formula A at prefix sigma
Read as: true possibility rule
Read as: true formula A at prefix sigma dot n
Read as: false possibly formula A at prefix sigma
Read as: false possibility rule
Read as: false formula A at prefix sigma dot n
Read as: true necessity rule
Read as: true necessarily formula A at prefix one
Read as: false possibly formula A at prefix one
Read as: true formula A at prefix one point one
Read as: false formula A at prefix one point one
Read as: false necessity rule
Read as: true possibly formula A at prefix one
Read as: false necessarily formula A at prefix one
Read as: true formula A at prefix one point one
Read as: false formula A at prefix one point one
Read as: false the conditional from the conjunction of necessarily formula A and necessarily formula B to necessarily the conjunction of formula A and formula B at prefix one
Read as: true the conjunction of necessarily formula A and necessarily formula B at prefix one
Read as: false necessarily the conjunction of formula A and formula B at prefix one
Read as: true necessarily formula A at prefix one
Read as: true necessarily formula B at prefix one
Read as: false the conjunction of formula A and formula B at prefix one point one
Read as: false formula A at prefix one point one
Read as: true formula A at prefix one point one
Read as: false formula B at prefix one point one
Read as: true formula B at prefix one point one
Read as: false the conditional from possibly the disjunction of formula A and formula B to the disjunction of possibly formula A and possibly formula B at prefix one
Read as: true possibly the disjunction of formula A and formula B at prefix one
Read as: false the disjunction of possibly formula A and possibly formula B at prefix one
Read as: false possibly formula A at prefix one
Read as: false possibly formula B at prefix one
Read as: true the disjunction of formula A and formula B at prefix one point one
Read as: true formula A at prefix one point one
Read as: false formula A at prefix one point one
Read as: true formula B at prefix one point one
Read as: false formula B at prefix one point one
Read as: true necessarily formula A at prefix sigma
Read as: true formula A at prefix sigma
Read as: false possibly formula A at prefix sigma
Read as: false formula A at prefix sigma
Read as: true necessarily formula A at prefix sigma
Read as: true possibly formula A at prefix sigma
Read as: false possibly formula A at prefix sigma
Read as: false necessarily formula A at prefix sigma
Read as: true necessarily formula A at prefix sigma dot n
Read as: true formula A at prefix sigma
Read as: false possibly formula A at prefix sigma dot n
Read as: false formula A at prefix sigma
Read as: true necessarily formula A at prefix sigma
Read as: true necessarily formula A at prefix sigma dot n
Read as: false possibly formula A at prefix sigma
Read as: false possibly formula A at prefix sigma dot n
Read as: true necessarily formula A at prefix sigma dot n
Read as: true necessarily formula A at prefix sigma
Read as: false possibly formula A at prefix sigma dot n
Read as: false possibly formula A at prefix sigma
Read as: false the conditional from necessarily formula A to necessarily possibly formula A at prefix one
Read as: true necessarily formula A at prefix one
Read as: false necessarily possibly formula A at prefix one
Read as: false possibly formula A at prefix one point one
Read as: false possibly formula A at prefix one
Read as: false formula A at prefix one point one
Read as: true formula A at prefix one point one
Read as: true necessarily formula A at prefix n
Read as: true necessity rule
Read as: true formula A at prefix m
Read as: false necessarily formula A at prefix n
Read as: false necessity rule
Read as: false formula A at prefix m
Read as: true possibly formula A at prefix n
Read as: true possibility rule
Read as: true formula A at prefix m
Read as: false possibly formula A at prefix n
Read as: false possibility rule
Read as: false formula A at prefix m
Read as: false the conditional from possibly formula A to necessarily possibly formula A at prefix one
Read as: true possibly formula A at prefix one
Read as: false necessarily possibly formula A at prefix one
Read as: false possibly formula A at prefix two
Read as: true formula A at prefix three
Read as: false formula A at prefix three
Read as: Case: A is the propositional variable p.
Read as: Case: A is the negation of B.
Read as: Case: A is the conjunction of B and C.
Read as: Case: A is the disjunction of B and C.
Read as: Case: A is the conditional from B to C.
Read as: Case: A is necessarily B.
Read as: Case: A is possibly B.
Read as: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one
Read as: true necessarily the disjunction of p and q at prefix one
Read as: false the disjunction of necessarily p and necessarily q at prefix one
Read as: false necessarily p at prefix one
Read as: false necessarily q at prefix one
Read as: false p at prefix one point one
Read as: false q at prefix one point two
Read as: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one
Read as: true necessarily the disjunction of p and q at prefix one
Read as: false the disjunction of necessarily p and necessarily q at prefix one
Read as: false necessarily p at prefix one
Read as: false necessarily q at prefix one
Read as: false p at prefix one point one
Read as: false q at prefix one point two
Read as: true the disjunction of p and q at prefix one point one
Read as: true the disjunction of p and q at prefix one point two
Read as: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one
Read as: true necessarily the disjunction of p and q at prefix one
Read as: false the disjunction of necessarily p and necessarily q at prefix one
Read as: false necessarily p at prefix one
Read as: false necessarily q at prefix one
Read as: false p at prefix one point one
Read as: false q at prefix one point two
Read as: true the disjunction of p and q at prefix one point one
Read as: true the disjunction of p and q at prefix one point two
Read as: true p at prefix one point one
Read as: true q at prefix one point one
Read as: true p at prefix one point two
Read as: true q at prefix one point two
Read as: p is false
Read as: q is false
Read as: p is false
Read as: q is true
Read as: p is true
Read as: q is false
Structure: table.
Propositional prefixed-tableau rule table. Propositional prefixed tableau rules. Row one, true negation: from true not A at prefix sigma, infer false A at prefix sigma. False negation: from false not A at prefix sigma, infer true A at prefix sigma. Row two, true conjunction: from true A and B at prefix sigma, stack true A and true B at that prefix. False conjunction: from false A and B at prefix sigma, branch to false A or false B at that prefix. Row three, true disjunction: from true A or B at prefix sigma, branch to true A or true B at that prefix. False disjunction: from false A or B at prefix sigma, stack false A and false B at that prefix. Row four, true conditional: from true if A then B at prefix sigma, branch to false A or true B at that prefix. False conditional: from false if A then B at prefix sigma, stack true A and false B at that prefix. End propositional rule table. End table.
Structure: table.
Four modal K rules. Headers: true-sign rule; false-sign rule. Row one, necessity. Premise true necessarily formula A at prefix sigma. Rule true necessity rule. Conclusion true formula A at prefix sigma dot n. Premise false necessarily formula A at prefix sigma. Rule false necessity rule. Conclusion false formula A at prefix sigma dot n. Side conditions: prefix sigma dot n; prefix sigma dot n. Row two, possibility. Premise true possibly formula A at prefix sigma. Rule true possibility rule. Conclusion true formula A at prefix sigma dot n. Premise false possibly formula A at prefix sigma. Rule false possibility rule. Conclusion false formula A at prefix sigma dot n. Side conditions: prefix sigma dot n; prefix sigma dot n. End modal K rule table.
Structure: tableau.
Closed necessity-versus-possibility tableau. Node one: true necessarily formula A at prefix one. Rule: tableau assumption. Node two: false possibly formula A at prefix one. Rule: tableau assumption. Node three: true formula A at prefix one point one. Rule: true necessity rule, depending on node one. Node four: false formula A at prefix one point one. Rule: false possibility rule, depending on node two; source close marker present. Branch one is closed, closed by nodes three and four. End tableau.
Structure: tableau.
Closed possibility-versus-necessity tableau. Node one: true possibly formula A at prefix one. Rule: tableau assumption. Node two: false necessarily formula A at prefix one. Rule: tableau assumption. Node three: true formula A at prefix one point one. Rule: true possibility rule, depending on node one. Node four: false formula A at prefix one point one. Rule: false necessity rule, depending on node two; source close marker present. Branch one is closed, closed by nodes three and four. End tableau.
Structure: tableau.
Tableau for necessity and conjunction. Node one: false the conditional from the conjunction of necessarily formula A and necessarily formula B to necessarily the conjunction of formula A and formula B at prefix one. Rule: tableau assumption. Node two: true the conjunction of necessarily formula A and necessarily formula B at prefix one. Rule: false conditional rule, depending on node one. Node three: false necessarily the conjunction of formula A and formula B at prefix one. Rule: false conditional rule, depending on node one. Node four: true necessarily formula A at prefix one. Rule: true conjunction rule, depending on node two. Node five: true necessarily formula B at prefix one. Rule: true conjunction rule, depending on node two. Node six: false the conjunction of formula A and formula B at prefix one point one. Rule: false necessity rule, depending on node three. Node seven: false formula A at prefix one point one. Rule: false conjunction rule, depending on node six. Node eight: true formula A at prefix one point one. Rule: true necessity rule, depending on node four; source close marker present. Node nine: false formula B at prefix one point one. Rule: false conjunction rule, depending on node six. Node one zero: true formula B at prefix one point one. Rule: true necessity rule, depending on node five; source close marker present. Branch one is closed, closed by nodes seven and eight. Branch two is closed, closed by nodes nine and one zero. End tableau.
Structure: tableau.
Tableau for possibility and disjunction. Node one: false the conditional from possibly the disjunction of formula A and formula B to the disjunction of possibly formula A and possibly formula B at prefix one. Rule: tableau assumption. Node two: true possibly the disjunction of formula A and formula B at prefix one. Rule: false conditional rule, depending on node one. Node three: false the disjunction of possibly formula A and possibly formula B at prefix one. Rule: false conditional rule, depending on node one. Node four: false possibly formula A at prefix one. Rule: false disjunction rule, depending on node three. Node five: false possibly formula B at prefix one. Rule: false disjunction rule, depending on node three. Node six: true the disjunction of formula A and formula B at prefix one point one. Rule: true possibility rule, depending on node two. Node seven: true formula A at prefix one point one. Rule: true disjunction rule, depending on node six. Node eight: false formula A at prefix one point one. Rule: false possibility rule, depending on node four; source close marker present. Node nine: true formula B at prefix one point one. Rule: true disjunction rule, depending on node six. Node one zero: false formula B at prefix one point one. Rule: false possibility rule, depending on node five; source close marker present. Branch one is closed, closed by nodes seven and eight. Branch two is closed, closed by nodes nine and one zero. End tableau.
Structure: table.
Additional modal rules. Headers: necessity form; possibility form. Row one, reflexive T. Premise true necessarily formula A at prefix sigma. Rule label T the necessity operator. Conclusion true formula A at prefix sigma. Premise false possibly formula A at prefix sigma. Rule label T the possibility operator. Conclusion false formula A at prefix sigma. Row two, serial D. Premise true necessarily formula A at prefix sigma. Rule label D the necessity operator. Conclusion true possibly formula A at prefix sigma. Premise false possibly formula A at prefix sigma. Rule label D the possibility operator. Conclusion false necessarily formula A at prefix sigma. Row three, symmetric B. Premise true necessarily formula A at prefix sigma dot n. Rule label B the necessity operator. Conclusion true formula A at prefix sigma. Premise false possibly formula A at prefix sigma dot n. Rule label B the possibility operator. Conclusion false formula A at prefix sigma. Row four, transitive four. Premise true necessarily formula A at prefix sigma. Rule label four the necessity operator. Conclusion true necessarily formula A at prefix sigma dot n. Premise false possibly formula A at prefix sigma. Rule label four the possibility operator. Conclusion false possibly formula A at prefix sigma dot n. Both prefixes are used: prefix sigma dot n; prefix sigma dot n. Row five, euclidean four r. Premise true necessarily formula A at prefix sigma dot n. Rule label four r the necessity operator. Conclusion true necessarily formula A at prefix sigma. Premise false possibly formula A at prefix sigma dot n. Rule label four r the possibility operator. Conclusion false possibly formula A at prefix sigma. End additional-rule table.
Structure: table.
Logic and tableau-rule correspondence. Headers: logic; accessibility relation R is; rules. Header formula accessibility relation R. Row one: T equals K T; reflexive; formulas logic T equals logic K T, then the necessity operator, then the possibility operator. Row two: D equals K D; serial; formulas logic D equals logic K D, then the necessity operator, then the possibility operator. Row three: K four; transitive; formulas logic K four, then the necessity operator, then the possibility operator. Row four: B equals K T B; reflexive and symmetric; formulas logic B equals logic K T B, then the necessity operator, then the possibility operator, then the necessity operator, then the possibility operator. Row five: S four equals K T four; reflexive and transitive; formulas logic S four equals logic K T four, then the necessity operator, then the possibility operator, then the necessity operator, then the possibility operator. Row six: S five equals K T four B; reflexive, transitive, and euclidean; formulas logic S five equals logic K T four B, then the necessity operator, then the possibility operator, then the necessity operator, then the possibility operator, then the necessity operator, then the possibility operator. End correspondence table.
Structure: tableau.
Tableau proof of axiom five in S five. Node one: false the conditional from necessarily formula A to necessarily possibly formula A at prefix one. Rule: tableau assumption. Node two: true necessarily formula A at prefix one. Rule: false conditional rule, depending on node one. Node three: false necessarily possibly formula A at prefix one. Rule: false conditional rule, depending on node one. Node four: false possibly formula A at prefix one point one. Rule: false necessity rule, depending on node three. Node five: false possibly formula A at prefix one. Rule: four r the possibility operator, depending on node four. Node six: false formula A at prefix one point one. Rule: false possibility rule, depending on node five. Node seven: true formula A at prefix one point one. Rule: true necessity rule, depending on node two; source close marker present. Branch one is closed, closed by nodes six and seven. End tableau.
Structure: table.
Simplified S five rules. Headers: true-sign rule; false-sign rule. Row one, necessity. Premise true necessarily formula A at prefix n. Rule true necessity rule. Conclusion true formula A at prefix m. Premise false necessarily formula A at prefix n. Rule false necessity rule. Conclusion false formula A at prefix m. Side conditions: prefix m; prefix m. Row two, possibility. Premise true possibly formula A at prefix n. Rule true possibility rule. Conclusion true formula A at prefix m. Premise false possibly formula A at prefix n. Rule false possibility rule. Conclusion false formula A at prefix m. Side conditions: prefix m; prefix m. End simplified S five rule table.
Structure: tableau.
Simplified S five tableau proof. Node one: false the conditional from possibly formula A to necessarily possibly formula A at prefix one. Rule: tableau assumption. Node two: true possibly formula A at prefix one. Rule: false conditional rule, depending on node one. Node three: false necessarily possibly formula A at prefix one. Rule: false conditional rule, depending on node one. Node four: false possibly formula A at prefix two. Rule: false necessity rule, depending on node three. Node five: true formula A at prefix three. Rule: true possibility rule, depending on node two. Node six: false formula A at prefix three. Rule: false possibility rule, depending on node four; source close marker present. Branch one is closed, closed by nodes five and six. End tableau.
Structure: tableau.
Initial unfinished countermodel tableau. Node one: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one. Rule: tableau assumption; source checkmark present. Node two: true necessarily the disjunction of p and q at prefix one. Rule: false conditional rule, depending on node one. Node three: false the disjunction of necessarily p and necessarily q at prefix one. Rule: false conditional rule, depending on node one; source checkmark present. Node four: false necessarily p at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node five: false necessarily q at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node six: false p at prefix one point one. Rule: false necessity rule, depending on node four; source checkmark present. Node seven: false q at prefix one point two. Rule: false necessity rule, depending on node five; source checkmark present. Branch one is unfinished. End tableau.
Structure: tableau.
Second unfinished countermodel tableau. Node one: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one. Rule: tableau assumption; source checkmark present. Node two: true necessarily the disjunction of p and q at prefix one. Rule: false conditional rule, depending on node one. Node three: false the disjunction of necessarily p and necessarily q at prefix one. Rule: false conditional rule, depending on node one; source checkmark present. Node four: false necessarily p at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node five: false necessarily q at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node six: false p at prefix one point one. Rule: false necessity rule, depending on node four; source checkmark present. Node seven: false q at prefix one point two. Rule: false necessity rule, depending on node five; source checkmark present. Node eight: true the disjunction of p and q at prefix one point one. Rule: true necessity rule, depending on node two. Node nine: true the disjunction of p and q at prefix one point two. Rule: true necessity rule, depending on node two. Branch one is unfinished. End tableau.
Structure: tableau.
Complete countermodel tableau. Node one: false the conditional from necessarily the disjunction of p and q to the disjunction of necessarily p and necessarily q at prefix one. Rule: tableau assumption; source checkmark present. Node two: true necessarily the disjunction of p and q at prefix one. Rule: false conditional rule, depending on node one; source checkmark present. Node three: false the disjunction of necessarily p and necessarily q at prefix one. Rule: false conditional rule, depending on node one; source checkmark present. Node four: false necessarily p at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node five: false necessarily q at prefix one. Rule: false disjunction rule, depending on node three; source checkmark present. Node six: false p at prefix one point one. Rule: false necessity rule, depending on node four; source checkmark present. Node seven: false q at prefix one point two. Rule: false necessity rule, depending on node five; source checkmark present. Node eight: true the disjunction of p and q at prefix one point one. Rule: true necessity rule, depending on node two; source checkmark present. Node nine: true the disjunction of p and q at prefix one point two. Rule: true necessity rule, depending on node two; source checkmark present. Node one zero: true p at prefix one point one. Rule: true disjunction rule, depending on node eight; source checkmark present; source close marker present. Node one one: true q at prefix one point one. Rule: true disjunction rule, depending on node eight; source checkmark present. Node one two: true p at prefix one point two. Rule: true disjunction rule, depending on node nine; source checkmark present. Node one three: true q at prefix one point two. Rule: true disjunction rule, depending on node nine; source checkmark present; source close marker present. Branch one is closed, closed by nodes six and one zero. Branch two is open and complete. Branch three is closed, closed by nodes seven and one three. End tableau.
Structure: diagram tikz.
Three-world countermodel graph. Node one is prefix one, with printed valuations p is false and q is false. Node two is prefix one point one, with printed valuations p is false and q is true. Node three is prefix one point two, with printed valuations p is true and q is false. Directed accessibility edges, in printed order: from world one to world one point one; then from world one to world one point two. No loop or further edge is printed. End graph.
Structure: proof tree.
From true not A at prefix sigma, infer false A at prefix sigma.
Structure: proof tree.
From false not A at prefix sigma, infer true A at prefix sigma.
Structure: proof tree.
From true A and B at prefix sigma, stack true A and true B at the same prefix.
Structure: proof tree.
From false A and B at prefix sigma, branch to false A or false B at the same prefix.
Structure: proof tree.
From true A or B at prefix sigma, branch to true A or true B at the same prefix.
Structure: proof tree.
From false A or B at prefix sigma, stack false A and false B at the same prefix.
Structure: proof tree.
From true if A then B at prefix sigma, branch to false A or true B at the same prefix.
Structure: proof tree.
From false if A then B at prefix sigma, stack true A and false B at the same prefix.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma. Rule true necessity rule. Conclusion true formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise false necessarily formula A at prefix sigma. Rule false necessity rule. Conclusion false formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise true possibly formula A at prefix sigma. Rule true possibility rule. Conclusion true formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma. Rule false possibility rule. Conclusion false formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma. Rule label T the necessity operator. Conclusion true formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma. Rule label T the possibility operator. Conclusion false formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma. Rule label D the necessity operator. Conclusion true possibly formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma. Rule label D the possibility operator. Conclusion false necessarily formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma dot n. Rule label B the necessity operator. Conclusion true formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma dot n. Rule label B the possibility operator. Conclusion false formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma. Rule label four the necessity operator. Conclusion true necessarily formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma. Rule label four the possibility operator. Conclusion false possibly formula A at prefix sigma dot n.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix sigma dot n. Rule label four r the necessity operator. Conclusion true necessarily formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix sigma dot n. Rule label four r the possibility operator. Conclusion false possibly formula A at prefix sigma.
Structure: proof tree.
Proof diagram. Premise true necessarily formula A at prefix n. Rule true necessity rule. Conclusion true formula A at prefix m.
Structure: proof tree.
Proof diagram. Premise false necessarily formula A at prefix n. Rule false necessity rule. Conclusion false formula A at prefix m.
Structure: proof tree.
Proof diagram. Premise true possibly formula A at prefix n. Rule true possibility rule. Conclusion true formula A at prefix m.
Structure: proof tree.
Proof diagram. Premise false possibly formula A at prefix n. Rule false possibility rule. Conclusion false formula A at prefix m.