How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
The same matrix can have two different numerical ranks under two declared tolerances
Statement refuted
Numerical rank is a property of the matrix alone, an exact invariant that does not depend on the declared tolerance.
Facts & Assumptions
Given: The diagonal matrix with singular values , , , and the two tolerances and .
In the spectral norm, (In the spectral norm, numerical rank counts the singular values above the declared threshold).
Counterexample
At the tolerance , the only singular value strictly above the threshold is , so [L1] gives .
At the tolerance , the singular values strictly above the threshold are and , so [L1] gives .
The singular value lies strictly between the two tolerances, , which is exactly why it is counted at but not at .
Steps 1.1, 1.2 and 1.3 exhibit one matrix and two declared tolerances with numerical ranks and : numerical rank is a function of the matrix together with the tolerance, not of the matrix alone, which refutes the false statement.
Depends on
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
5 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- David Bindel, CS 6210: Matrix Nearness Problems (standard reference, not scraped)