Matrix-power and reversible-rewriting review evidence

matrix_vass_review.py is a dependency-free exact checker for the two reviewed result units. It performs four bounded audits:

• Cayley–Hamilton recurrences and the entry-interleaving construction for all 81 two-by-two matrices over {-1,0,1};
• periodic nonnegative-power sets for every signed permutation matrix through dimension five;
• the first nonnegative power of the one-negative-edge signed cycles of lengths 3, 5, 7, and 11;
• reversible reachability versus independently implemented Gröbner-basis ideal membership for 72 finite degree-preserving systems, plus a directed hostile control.

Run with python matrix_vass_review.py. The script writes its JSON result to standard output; independent-output.json is the committed transcript. These finite computations test reductions and boundary examples. They do not replace the unrestricted proofs in the cited primary sources.