Theorem · orbit invariant

QA-HUR-FIB-T08

Attainable products are Hurwitz invariant

Exact statement

The complete attainable-product set of an admissible lift fibre is invariant under quotient Hurwitz moves; each move bijects Cartesian lift fibres while preserving total product.

StatusProved
External reviewNo documented external or specialist review of this Quotient Arsenal result is recorded.

Context

Finite quotient words do not lift one factor at a time independently. Local affine lift fibres must be transported through the ordered product; the target defect then lives in a product-image cokernel that is invariant under quotient Hurwitz moves.

Proof or evidence

The Hurwitz move and its inverse act factorwise and preserve the ordered product exactly.

Verification notes

The ordered-product proof was reconstructed with its square-zero and mod-eight domains explicit. An independent implementation checked 69,632 affine/quadratic matrix identities and 1,625 relative Nielsen and split-central identities, including an order-reversal hostile control.

Limitations

  • The admissible local lift sets must be conjugation-compatible.

Open work

Use product-image rank and target membership as quotient-orbit receipts.