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Unit 4 — Citation, Provenance, and the Source Notebook

Connecting each claim to its version, location, evidence, and limits of certainty

A practical unit on distinguishing citation from evidence provenance and computational provenance, maintaining a source notebook, and auditing mathematical corrections without erasing version history.

1 Learning outcomes

This unit has the stable identifier O017-U04. After completing it, you will be able to:

  1. distinguish the functions of citation, evidence provenance, and computational provenance without substituting one for another;
  2. record works, versions, copies, and internal locations as distinct but connected objects;
  3. connect a normalized claim to a locator precise enough for another reader to find the wording that was actually examined;
  4. retain the grounds for accepting, rejecting, or qualifying a mathematical claim, rather than merely retaining its bibliography;
  5. record corrections as relationships between versions without overwriting or deleting the historical state of an earlier source;
  6. record uncertainty in a structured way and refuse to fill missing metadata with guesses;
  7. design a source notebook that can be updated, reviewed, and exported without losing the decision trail; and
  8. assemble a claim dossier that brings together citation, provenance, mathematical audit, and the limits of the conclusions.
NotePrerequisites, continuity, and scope

Unit 2 teaches you to find candidate sources, distinguish a work from a version, and assess its authority. Unit 3 teaches you to close proof gaps through lemma contracts and dependency graphs. Unit 4 assumes that both kinds of work have been done, then preserves the trail connecting their results: which claim, which wording, which version, which location, which evidence, which decision, and what remaining uncertainty.

This unit does not teach a particular bibliography style, reference-manager use, database syntax, Git commands, checksum calculation, or computational environment setup. Tool formats may change; the logical relationships that must be preserved do not.

2 A bibliography is not yet an evidence trail

A bibliography entry usually answers questions such as “Which work is being referenced?” and “How can the reader identify it?” For a mathematical audit, that is not enough.

Consider the sentence:

This result follows from Source A.

At least seven questions remain open.

  1. Which edition or version of Source A?
  2. Did the reader examine the full text or only its metadata?
  3. On which page, or in which section, theorem, equation, or paragraph, does the result appear?
  4. Is its wording the same as the claim being used?
  5. Do all its hypotheses match?
  6. Was there a correction after that version?
  7. Does “follows from” mean cited, proved, tested with examples, or merely considered plausible?

A good source record does not turn a citation into a long story. It adds structure that allows each question above to be answered, or honestly marked not yet known.

ImportantOriginal O017 bridge material

The claim–locator–version chain model, separation of three kinds of records, uncertainty statuses, layered notebook, and mathematical cases in this unit are original O017 bridge material. General concepts of metadata, versions, citation of research objects, and computational provenance are restricted to the frozen donors; the donors do not provide the complete workflow for auditing mathematical claims developed here.

3 Three records with three different jobs

The following three terms often appear within one project, but answer different questions.

Record Main question Minimum contents Does not by itself establish
Citation Which work or object should receive credit and be discoverable? creator, title, publication venue, year, identifier or URL, version where relevant that the cited claim is true or its hypotheses match
Evidence provenance Exactly where do this claim’s wording and the grounds for the decision about it come from? claim ID, version ID, locator, evidence type, relationship, decision, reason, uncertainty that a computational process can be rerun
Computational provenance Which artifacts and conditions produced a particular computational output? code, inputs, dependencies, runtime, parameters, command or procedure, outputs, byte identity that finite outputs prove a universal claim

These can overlap. A code package can be cited; one of its outputs can serve as empirical evidence; its execution record can retain computational provenance. But one DOI does not replace an execution record, and one execution record does not replace a theorem’s proof.

3.1 Citation provides credit and a route to discovery

Choose the citation to match the object actually used. If a reader relies on the wording of a particular version, a version citation is more appropriate than a general work record. If a reader recommends that others look for the latest version, a work record may be more appropriate. Unit 2 introduced this distinction; here the choice is recorded as a decision, together with its reason.

3.2 Evidence provenance is a chain of accountability

Evidence provenance connects at least four objects:

[normalized claim] -> [locator] -> [version examined] -> [work]
         |
         +-> [proof / counterexample / data / reference]
         |
         +-> [decision + reason + uncertainty]

Arrows must have meanings. appearsAt differs from provedBy, refutedBy, correctedBy, and isVersionOf. A source can contain a false claim; an appearsAt arrow must therefore not be read as provedBy.

3.3 Computational provenance records the history of a particular result

For a computational result, record enough objects and conditions for someone with B80 skills to attempt a rerun. A record that merely says “calculated using Python” does not identify the program, inputs, dependency versions, parameters, or intended outputs.

This unit assesses the completeness and claim scope of that record. Writing programs, installing packages, choosing numerical types, writing tests, and generating checksums remain within B80. Even a perfect record only guarantees that a result is traceable; successful rerunning must be demonstrated by an execution that actually took place.

4 Four levels of source identity

The notebook must distinguish the following four levels.

  1. Work. An intellectual identity that may have many editions or versions.
  2. Version. The state of a work at a particular date, release, edition, revision, or commit.
  3. Copy. The bytes or physical object actually examined: a local file, printout, archive, or capture that may be incomplete.
  4. Location. A part within a version or copy: a page, theorem, equation, paragraph, line, or stable anchor.

A page number without an edition may point to different text. A version without a location makes readers search the entire document again. A copy’s checksum without the work’s identity preserves the bytes but does not explain their intellectual content. All four levels are needed when the risk of miscitation is sufficiently high.

Field Question answered Rule for completing it
source_id which record is being referenced? stable local ID; never reuse it
work_id which intellectual work? link all versions that genuinely belong to the same work
version_id which state of the work? edition/release/commit/date; record an unknown value when evidence is insufficient
copy_id which copy was examined? form, storage location, completeness, and byte identity where available
locator where was the content found? use the strongest scheme available in the source; section and page may be combined
relation how are the records related? typed directional verb, such as a correction or version relation
rights what are the component’s rights and obligations? license, attribution, and restrictions supported by evidence
observed_at when was the examination performed? observation date, not publication date
missing which fields remain unknown? explicit list; do not invent values

5 A two-layer source notebook

A notebook that withstands change has two layers.

5.1 The object layer

The object layer stores what is currently known about works, versions, copies, locations, claims, evidence, and executions. Each object has a stable ID. If a title is corrected, the ID does not change; the new value is given a supporting basis and a date. If two records turn out to refer to different works, do not merge them merely because their titles are similar.

5.2 The event layer

The event layer is an append-only log that does not overwrite earlier entries. For example:

  • 2026-08-21T09:10 — LOC-01 observedIn VERSION-01;
  • 2026-08-21T09:24 — CLAIM-01 refutedBy ARG-CE01;
  • 2026-08-21T09:31 — VERSION-02 corrects VERSION-01;
  • 2026-08-21T09:42 — DEC-01 changedFrom uncertain to rejected.

If a decision changes, add a new decision with its reason and a link to the old one. Do not alter an earlier record as if the error had never occurred. A notebook is not just a final picture; it also explains how that picture was obtained.

5.3 Seven tables are enough for many projects

The implementation may use paper, plain text, a spreadsheet, or a database. Conceptually, the following seven tables suffice for many mathematical reading projects.

Table Key Core contents
works work_id title, creators, publication venue, work identity
versions version_id version/edition/commit, date, relationships to the work and other versions
copies copy_id version embodied, format, copy location, copy completeness, byte identity or copy characteristics actually observed
locators locator_id copy and version, location scheme, location value, short quotation or controlled paraphrase
claims claim_id normalized statement, quantifiers, domain, status
evidence evidence_id evidence type, target claim, grounds, direction of support, limits
events event_id time, recorder, action, object, reason

Computational records may form an eighth table or a separate artifact linked from the evidence table. This separation prevents a single claim row from holding the entire computational environment and becoming unreadable.

6 A protocol from claim to notebook

Use this sequence for every claim important enough to cite.

  1. Freeze the working statement. Write the claim with explicit quantifiers, domain, and hypotheses; assign a claim_id.
  2. Identify the source objects. Separate the work, version, and copy actually examined. Record missing fields.
  3. Create a locator. Choose a location that remains meaningful for that version. Record its start and end if a claim spans several paragraphs.
  4. Record factual relationships. Record VERSION-02 as correcting VERSION-01; then locate CLAIM-01 at LOC-01. Do not insert mathematical conclusions into bibliographical relationships.
  5. Audit the mathematics. Link a proof, reconstruction, counterexample, or computational result as separate evidence.
  6. Decide the status. Use accepted, rejected, qualified, or not yet established, then state the reason and scope.
  7. Choose the citation. Choose the work or version according to the purpose of the sentence to be written; record the reason for the choice.
  8. Retain uncertainty and events. Add what remains unknown and any changes in decisions; do not clean away the history after a correction.

The protocol ends when another reader can follow the chain without guessing the version, location, meaning of an arrow, or reason for a status.

7 Worked case: an integral claim with a missing rate

The following case is entirely synthetic and embedded in this unit. Its IDs are classroom IDs, not DOIs or public identifiers. The aim is not to find a source outside this unit, but to build a correct notebook from a limited excerpt packet that is complete for this case. The packet does not represent the full contents of a book.

7.1 The version and correction packet

WarningPartial excerpt packet — Proposition 4.1, label V1

V1. If f:[0,1]f:[0,1]\to\mathbb{R} is continuous and f(0)=0f(0)=0, then the improper integral

01f(x)xdx \int_0^1 \frac{f(x)}{x}\,dx

converges.

NotePartial excerpt packet — correction item K-04

The hypotheses of continuity and f(0)=0f(0)=0 do not control the rate at which f(x)f(x) tends to zero. Version 1 of Proposition 4.1 is withdrawn. The next version replaces it with a sufficient growth condition; the correction does not claim that the new condition is necessary.

Theorem 1 V2. Let f:[0,1]f:[0,1]\to\mathbb{R} be continuous. If there exist C0C\geq0 and α>0\alpha>0 such that

|f(x)|Cxαfor every 0<x1, |f(x)|\leq Cx^\alpha \qquad\text{for every }0<x\leq1,

then the integral 01f(x)/xdx\int_0^1 f(x)/x\,dx converges absolutely.

7.2 Work and version records

We create IDs without bibliographical meanings embedded in them. Relationships and metadata belong in separate fields.

The exact relation isPropositionExcerptOf is abbreviated as IPEO only in the two narrow human-readable tables below. Machine-readable records retain the full relation name.

ID Type Identity and location Relationships Integrity and missing fields
O017-U04-W01 synthetic work identity Elementary Analysis Notes; creator: O017 contributors; year: 2026 conceptual parent object for the proposition excerpts the packet does not contain the complete work, so the contents of other sections, publisher, and publication form are unknown
O017-U04-V01 proposition-excerpt version wording of Proposition 4.1, version 1, as given in the packet IPEO W01 establishes only the wording of the quoted proposition, not the state of the entire book or notes
O017-U04-K01 correction excerpt item K-04 at LOC02; corrects V01; motivates V02 a separate correction date is not provided in the packet and is recorded as unknown
O017-U04-V02 proposition-excerpt version wording of Proposition 4.1, version 2, as given in the packet IPEO W01 establishes only the wording of the replacement proposition; there are no grounds to assert that the whole work has been replaced
O017-U04-CP01 partial excerpt packet three synthetic text excerpts embedded in Unit 4: V01, K01, and V02 physical scope is limited to these three excerpts not a complete copy of W01; its completeness means only that all three packet excerpts are available; byte identity is in the artifact manifest
O017-U04-LOC01 location V1 excerpt located in V01; part of CP01 stable anchor within the partial excerpt packet
O017-U04-LOC02 location correction K-04 part of CP01 stable anchor within the partial excerpt packet
O017-U04-LOC03 location V2 theorem located in V02; part of CP01 stable anchor within the partial excerpt packet

The labels V01 and V02 apply to the Proposition 4.1 excerpts within the packet, not to two complete copies of Elementary Analysis Notes. Decision D03 below selects V02 for current use of the proposition. That decision does not add a relationship saying “the whole book V2 replaces the whole book V1,” nor does it mean that V01 may be deleted: the history of the error and its correction is itself part of the provenance.

7.3 Freezing two claims

Claim ID Normalized statement Appears at Initial status
O017-U04-C01 for every fC([0,1])f\in C([0,1]) with f(0)=0f(0)=0, the integral 01f(x)/xdx\int_0^1 f(x)/x\,dx converges LOC01 in proposition excerpt V01 requires audit
O017-U04-C02 for every fC([0,1])f\in C([0,1]), C0C\geq0, and α>0\alpha>0 with |f(x)|Cxα|f(x)|\leq Cx^\alpha on (0,1](0,1], the integral converges absolutely LOC03 in proposition excerpt V02 requires audit

Claims C01 and C02 are not two wordings of the same statement. C02 has an additional hypothesis and a stronger conclusion, namely absolute convergence. The notebook therefore stores two claim_id values rather than silently changing the contents of C01.

7.4 Rejecting C01 with a counterexample

Define f:[0,1]f:[0,1]\to\mathbb{R} by

f(0)=0,f(x)=1log(e/x)(0<x1). f(0)=0, \qquad f(x)=\frac{1}{\log(e/x)}\quad (0<x\leq1).

This function is continuous on (0,1](0,1]. As x0x\downarrow0, log(e/x)\log(e/x)\to\infty, so f(x)0=f(0)f(x)\to0=f(0). Thus ff is continuous on all of [0,1][0,1] and satisfies the hypotheses of C01.

However, for 0<ε<10<\varepsilon<1, the substitution u=log(e/x)u=\log(e/x) gives du=dx/xdu=-dx/x and

ε1f(x)xdx=ε1dxxlog(e/x)=1log(e/ε)duu=log(log(e/ε)). \int_\varepsilon^1 \frac{f(x)}{x}\,dx =\int_\varepsilon^1\frac{dx}{x\log(e/x)} =\int_1^{\log(e/\varepsilon)}\frac{du}{u} =\log\!\bigl(\log(e/\varepsilon)\bigr).

As ε0\varepsilon\downarrow0, the final expression tends to ++\infty. The improper integral does not converge. This is deductive evidence that C01 is rejected, not merely a collection of numerical values that seem to grow.

Record the evidence as object O017-U04-EV01, with type counterexample and relationship C01 refutedBy EV01. Its exact basis locator is #o017-u04-v1-counterexample. Its limit is: “refutes the universal claim C01; does not say that every continuous function with f(0)=0f(0)=0 produces divergence.”

7.5 Accepting C02 with a comparison proof

Proof 1. Take ff, CC, and α\alpha satisfying the hypotheses of C02. For every 0<x10<x\leq1,

|f(x)x|Cxα1. \left|\frac{f(x)}{x}\right| \leq Cx^{\alpha-1}.

Since α>0\alpha>0, the comparison integral exists and

01Cxα1dx=Cα<. \int_0^1 Cx^{\alpha-1}\,dx=\frac{C}{\alpha}<\infty.

Hence

01|f(x)x|dxCα<. \int_0^1\left|\frac{f(x)}{x}\right|\,dx \leq\frac{C}{\alpha}<\infty.

Thus the integral stated in C02 converges absolutely.

Record this proof as O017-U04-EV02, type proof, relationship C02 provedBy EV02, and location #prf-o017-u04-v2. Its limit matters: the proof establishes that the power-law condition is sufficient. It does not establish that every convergent integral must satisfy some bound CxαCx^\alpha.

7.6 The claim-to-locator chain

After the audit, a compact provenance graph is:

C01 --appearsAt--> LOC01 --locatesIn--> V01 --isPropositionExcerptOf--> W01
                       |
                       +--partOf--> CP01
  |
  +--refutedBy--> EV01 (counterexample and exact integral)

K01 --appearsAt--> LOC02 --partOf--> CP01
K01 --corrects--> V01
K01 --motivates--> V02 --isPropositionExcerptOf--> W01

C02 --appearsAt--> LOC03 --locatesIn--> V02
                       |
                       +--partOf--> CP01
  |
  +--provedBy--> EV02 (comparison proof)

This graph answers two questions separately: where a claim appears and why its mathematical status was assigned. Removing either branch would obscure the source or the grounds for the decision.

The following semantic table communicates the same relationships without relying on the visual arrangement of characters in the graph. This table is the authoritative list of relationships for this unit’s exercises and audit.

Subject Relationship Object Grounds or function
C01 appearsAt LOC01 observation of the packet’s wording
LOC01 locatesIn V01 location of the claim in proposition excerpt V01
LOC01 partOf CP01 membership in the partial packet
V01 IPEO W01 scope limited to the Proposition 4.1 excerpt
C01 refutedBy EV01 counterexample and exact integral
K01 appearsAt LOC02 observation of the correction text
LOC02 partOf CP01 membership in the partial packet
K01 corrects V01 relationship stated by text K01
K01 motivates V02 relationship stated by text K01
V02 IPEO W01 scope limited to the Proposition 4.1 excerpt
C02 appearsAt LOC03 observation of the packet’s wording
LOC03 locatesIn V02 location of the claim in proposition excerpt V02
LOC03 partOf CP01 membership in the partial packet
C02 provedBy EV02 comparison proof

7.7 The decision and uncertainty notebook

Decision ID Claim Status Grounds Limits and uncertainty
O017-U04-D01 C01 rejected EV01 satisfies the hypotheses but the integral diverges the historical reason for the V1 error is unknown; it is not needed for rejection
O017-U04-D02 C02 accepted EV02 proves the conclusion from all the hypotheses sufficient condition, not claimed to be necessary or optimal
O017-U04-D03 excerpt relationship qualified K01 corrects V01 and motivates proposition excerpt V02 the packet does not establish the state of the complete work, a separate correction date, or a public identifier

The word accepted always has a scope: claim C02 as normalized, on the basis of the recorded argument. It is not a comprehensive assessment of the whole work W01.

Use the following uncertainty vocabulary.

  • known: an observation or argument is available, with a locator.
  • inferred: there is an explicit inference from recorded facts; state the reason.
  • disputed: two relevant pieces of evidence or sources conflict.
  • unknown: the available evidence does not answer the question.
  • not applicable: the field genuinely has no meaning for this object.

Do not replace unknown with a confidence number unsupported by a model or data. In this case, an external creator for W01 is not applicable because O017 created the synthetic packet; a separate correction date is unknown because the packet deliberately does not supply one.

7.8 Choosing a citation after the audit

Three kinds of sentences require different choices.

  1. For the history of the error, cite V1 and K01: readers need to see both the incorrect wording and its correction.
  2. To use the valid result, cite V2 at Proposition 4.1 and, space permitting, link EV02 as the local audit.
  3. To mention the packet generally without relying on particular wording, W01 suffices, provided the sentence does not imply that all its versions are identical.

A V2 citation provides credit and a route to discovery. The status accepted still comes from EV02, not from the fact that V2 is newer.

7.9 Where does computational provenance enter?

The proof above requires no computation. Suppose a reader also produces a table of log(log(e/ε))\log(\log(e/\varepsilon)) for several values of ε\varepsilon. The table may help reveal growth, but does not replace the exact limit. An adequate execution record has at least the following form.

Field Contents to fill in after an actual execution
run_id stable ID for one execution
code_artifact file and byte identity of the code actually run
input list of ε\varepsilon values and their numerical format
environment runtime and dependencies with observed versions
parameters all options that change the result
invocation exact command or procedure used, including the working directory if it matters
output output file/table and its byte identity
claim_scope “illustration of growth on selected inputs,” not “proves divergence”
status_pelaksanaan_ulang rerun status: not yet attempted / succeeded / failed, with time and evidence

This table is a template, not a claim that an execution has occurred. Filling it with invented values to make it appear complete would undermine the provenance.

8 Corrections do not erase earlier versions

When a correction is found, take five actions.

  1. Freeze the earlier version’s identity and the location of the affected claim.
  2. Record the correction as a separate object with a locator and directional relationships.
  3. Create a new claim if the hypotheses or conclusion change.
  4. Update the decision about current use, but retain earlier decisions in the event log.
  5. Check all derivative writing that cites the earlier claim; do not assume that replacing one bibliography entry repairs its argument.

A new version is not automatically more correct. It is merely a new candidate to audit. Conversely, finding an error in one proposition does not justify declaring the entire work useless.

9 Guided practice: one traceable line

Start from the sentence “version 2 repairs the condition in version 1.” Break it into six records:

  1. V01 and V02 as two proposition-excerpt versions of W01;
  2. LOC01 and LOC03 as two locators;
  3. C01 and C02 as two normalized claims;
  4. K01 as a correction object that corrects V01;
  5. EV01 and EV02 as different mathematical grounds; and
  6. D01 and D02 as decisions with stated scopes.

Now try removing EV01. The trail still shows that a correction was stated, but no longer independently shows that C01 is false. Remove LOC01: the counterexample still refutes C01, but the reader can no longer check whether C01 really is V1’s wording. This deletion test shows why source provenance and evidence must connect without being conflated.

10 Exercises

  1. O017-U04-E01. Classify each of the following records as citation, evidence provenance, computational provenance, or a combination: (a) a work DOI; (b) “Theorem 3.7, page 82, second edition”;

    1. a code file, runtime version, parameters, and output checksum; (d) a counterexample linked to C01; (e) an author’s name and title; (f) a rejected decision with EV01 as its reason. For each item, explain one question that it still leaves unanswered.
  2. O017-U04-E02. A note says only “Lemma 5 in the blue book proves this result.” Turn it into an auditable record scheme: work, version, copy, location, normalized claim, lemma contract, and fields that remain unknown. Do not invent an author, year, or page number.

  3. O017-U04-E03. Using the semantic relationship table as the authoritative list, separate arrows that record source observations from arrows that record mathematical conclusions. Do K01 corrects V01, K01 motivates V02, and C02 provedBy EV02 derive their support from the same object? Explain.

  4. O017-U04-E04. For 0<β10<\beta\leq1, take fβ(x)=xβf_\beta(x)=x^\beta. Determine whether the function satisfies C01 and C02, calculate 01fβ(x)/xdx\int_0^1 f_\beta(x)/x\,dx, then explain why this successful family of examples does not rescue the universal claim C01.

  5. O017-U04-E05. Suppose the packet adds a Proposition 4.1 excerpt labelled V03 with the same mathematical wording as V02, but a different layout and page numbering. State which objects remain, which are new, which relationships must be added, and why the citation “p. 9” without an excerpt version is insufficient. Distinguish a content change from a locator change.

  6. O017-U04-E06. Design a record for a numerical experiment that evaluates the truncated integral at five values of ε\varepsilon. Do not write code. Specify the inputs, artifacts, environment, parameters, invocation command or procedure, outputs, rerun status, and a claim-scope sentence that prevents five samples from being treated as a proof of the limit.

11 Hints and answer guidance

  1. O017-U04-H01. (a) and (e) are primarily citation;

    1. is a discovery element that becomes part of evidence provenance when linked to a claim and version; (c) is computational provenance; (d) and
    2. are evidence provenance. No one item alone establishes source identity, the claim’s truth, and the ability to rerun a computation all at once.
  2. O017-U04-H02. Create local IDs for the work, version, copy, location, claim, and lemma. Enter only “blue-covered book” as an observed characteristic of the copy. Author, official title, edition, year, and page number remain unknown until evidence is available. The lemma contract must compare all its hypotheses with the claim’s context.

  3. O017-U04-H03. K01 corrects V01 and K01 motivates V02 are two source relationships both supported by text K01. Neither proves C02. The relationship C02 provedBy EV02 is grounded in proof EV02 and records a mathematical conclusion. Source relationships and grounds for truth must not be conflated.

  4. O017-U04-H04. Take C=1C=1 and α=β\alpha=\beta; then C02 applies and the integral is 1/β1/\beta. These examples also satisfy C01, but one counterexample suffices to refute a universal claim, whereas many positive examples do not prove it.

  5. O017-U04-H05. W01 remains, and V03 is a new proposition-excerpt version.

    isPropositionExcerptOf links V03 to W01.

    hasSamePropositionTextAs links V03 to V02 only when evidence supports it.

    LOC03 still points to V02, while V03 needs a new locator because its pagination has changed. Do not use corrects if the mathematical content has not changed.

  6. O017-U04-H06. The record must identify one execution, not “the program in general,” and must retain the command or sequence of procedures actually used. An appropriate scope statement is, for example: “the five outputs show increasing values on the selected inputs and serve as a diagnostic; divergence is established by the exact limit calculation EV01.” Rerun status must not be succeeded before a second execution has actually taken place.

12 Unit completion task

Assemble a citation and provenance dossier for the following synthetic packet. All IDs are nonpublic classroom IDs.

WarningMatrix Norm Notes, V1 — Proposition 2.6

For every real 2×22\times2 matrix, the Euclidean operator norm satisfies A22=A22\lVert A^2\rVert_2=\lVert A\rVert_2^2.

NoteCorrection C-2.6

The equality in Proposition 2.6 does not hold in general. Replace it with A22A22\lVert A^2\rVert_2\leq\lVert A\rVert_2^2. There is no change to the definition A2=supx0Ax2/x2\lVert A\rVert_2=\sup_{x\ne0}\lVert Ax\rVert_2/\lVert x\rVert_2.

ImportantMatrix Norm Notes, V2 — Proposition 2.6

For every real 2×22\times2 matrix, the Euclidean operator norm satisfies A22A22\lVert A^2\rVert_2\leq\lVert A\rVert_2^2.

The dossier must contain:

  1. separate records for the work, V1, correction, V2, one partial copy/packet, all three locators, and all directional relationships; explicitly state that the packet is incomplete and link each locator to both its copy and its version;
  2. two normalized claims with quantifiers, domain, and unambiguous norm notation;
  3. a counterexample to V1 using A=(0100)A=\begin{pmatrix}0&1\\0&0\end{pmatrix}: prove A2=0A^2=0 and A2=1\lVert A\rVert_2=1, rather than merely stating software output;
  4. a proof of V2 directly from the operator-norm definition, showing A2x2A2Ax2\lVert A^2x\rVert_2\leq\lVert A\rVert_2\lVert Ax\rVert_2 and then taking the appropriate supremum;
  5. evidence objects, decisions with explicit scopes, and a claim–locator–copy–version–work graph for both claims;
  6. one citation for discussing the history of the error and one for using the valid result, with reasons for the choices;
  7. a list of metadata that is available, unknown, and not applicable, without inventing a DOI, author, date, or checksum;
  8. a proposed computational provenance record for checking candidate matrices, labelled not yet executed unless there is evidence of an actual execution; and
  9. a statement of limits: explain why the example matrix refutes the universal equality but does not show that the equality fails for every matrix.

12.1 Rubric

Score each criterion 0, 1, or 2.

Criterion 0 1 2
Identity and versions work, version, and copy are conflated some objects are separated all objects, locators, and version relationships are explicit
Claims and locations claims are not normalized or lack locations quantifiers/locations are partly complete both claims are precise and linked to locations in their respective versions
Mathematical audit example or proof is incorrect correct idea with gaps the example’s norm is calculated and submultiplicativity is fully proved
Evidence provenance citation is used as proof some relationships/grounds are recorded occurrence, refutation, proof, decision, and limits are separated
Computational provenance results or executions are invented a template exists but scope/status is unclear all minimum fields are present, status is honest, and empirical scope is bounded
Uncertainty and exposition metadata is guessed or history is overwritten some missing fields are visible missing data has a status, the correction preserves V1, and citations match their purposes

A passing score is at least 10 out of 12, with a score of 2 for Mathematical audit, Evidence provenance, and Uncertainty and exposition. Deleting V1 after finding a correction, treating V2 as true merely because it is newer, inventing metadata, or claiming an execution that did not take place requires revision even if the total score is sufficient.

13 Boundaries with B80 and other units

This unit does not teach Python, SageMath, SymPy, or NumPy/SciPy syntax, reference-manager APIs, particular database schemas, Git commands, checksum generation, environment management, or test writing. Those implementation skills all belong to B80. This unit specifies only what information must be preserved and how to limit conclusions drawn from computational results.

Unit 4 also does not repeat Unit 2’s search strategies and authority matrix, Unit 3’s gap reconstruction, Unit 5’s full exposition writing, Unit 6’s reproducibility package, or Unit 7’s erratum format. The notebook created here will supply inputs to those units: it preserves identities and decisions, while later units teach the products that use them.

14 Sources, provenance, changes, and rights

The original Indonesian prose, claim–locator–version chain model, two-layer notebook, decision tables, integral and matrix-norm packets, counterexamples, proofs, exercises, answer guidance, completion task, and rubric in this unit are original O017 material by the O017 contributors, 2026, licensed under CC BY-SA 4.0. This English translation retains that attribution and license.

General concepts of citation metadata, work and version identifiers, and version relationships were reviewed and adapted in a bounded way from The Turing Way (The Turing Way Community 2025, 2026), The Turing Way Community, at the fixed commit:

c98a0e6…131d1ce, specifically:

  • book/website/communication/citable/citable-versioning.md; and
  • book/website/communication/citable/citable-metadata.md.

That donor material is licensed under CC BY 4.0. The concepts used have been summarized, bounded, reorganized, and contextualized; no donor sentences, images, or exercises were copied.

The distinction between elements of computational provenance and per-result documentation was reviewed from Research Software Engineering with Python (Irving et al. 2021, n.d.) by Damien Irving, Kate Hertweck, Luke Johnston, Joel Ostblom, Charlotte Wickham, and Greg Wilson, at the fixed commit 62217e66…a3cf07, specifically chapters/provenance.Rmd. The selected local copy is:

selected-slice/provenance-selected.Rmd

The donor prose is licensed under CC BY 4.0. This unit copies no code, images, quotations, or external activities from the donor.

All adaptations have been newly contextualized for mathematical source auditing and changed substantively. The Turing Way Community, the six authors of Research Software Engineering with Python, their publishers, and their affiliations do not endorse, approve, or sponsor O017.

The calculus facts about the integral of xα1x^{\alpha-1} and the submultiplicativity of the operator norm are standard mathematical results. O017 does not claim to have discovered them; the proofs’ wording and pedagogical roles are original to this unit. Frozen sources remain subject to their own rights. The CC BY-SA 4.0 license for original O017 material does not replace or relicense donor components.

References

Irving, Damien, Kate Hertweck, Luke Johnston, Joel Ostblom, Charlotte Wickham, and Greg Wilson. 2021. Research Software Engineering with Python: Building Software That Makes Research Possible. Chapman & Hall/CRC Press. https://third-bit.com/py-rse/.
Irving, Damien, Kate Hertweck, Luke Johnston, Joel Ostblom, Charlotte Wickham, and Greg Wilson. n.d. Research Software Engineering with Python: Frozen Source Witness. https://github.com/merely-useful/py-rse/tree/62217e6606842ab9752fcf8e73954d1eb4a3cf07.
The Turing Way Community. 2025. The Turing Way Handbook for Reproducible, Ethical and Collaborative Research. Version 1.2.3. https://doi.org/10.5281/zenodo.3233853.
The Turing Way Community. 2026. The Turing Way Handbook for Reproducible, Ethical and Collaborative Research: Frozen Source Witness. https://github.com/the-turing-way/the-turing-way/tree/c98a0e6ca47450456cca7c5eedda2d5ee131d1ce.