Context
The exact reformulation survives the factorial counterexample, but finite generation of the visible derivative algebra does not.
Hypotheses and scope
- Polynomial/Hadamard automata over the rationals.
Proof or evidence
The exact reformulation and the failed derivative-algebra route isolate existence of a finite commutative over-algebra as the remaining obligation.
Verification notes
The public page explicitly separates proved partial results from this unresolved universal claim.
Limitations
- No counterexample to the originating question is established here.
- No claim is made that the problem is open in the published literature beyond the bounded source search.