FPRD-C02 · FPRD Lab

Claim FPRD-C02

Exact statement

There exists a deterministic visibly pushdown language whose call, return, and local annotations forget to a language outside PEL. Forgotten-action deterministic visible projections are exactly CFL by FPRD-T91, while Kim and Park exhibit a linear context-free language outside PEG. The universal question is therefore resolved negatively.

Statussource verified

External reviewNo documented external or specialist review of this FPRD result is recorded.

Context

This row is imported exactly from the governed FPRD claims ledger. The matrix assignment records normalized inventory coverage; it is not a new proof or a promotion of the ledger status.

Proof or evidence

The ledger points to docs/specs/post-m33-dyck-annotation-forgetting.md. The matrix has not yet rewritten that source into a self-contained public proof summary.

docs/specs/post-m33-dyck-annotation-forgetting.md →

Verification notes

Reviewed on 2026-08-25 for identifier, status, provenance, evidence-link presence, and dependency import only. Mathematical proof audit remains the next action unless separately documented.

Limitations

FPRD-T164 closes the former open target by composing FPRD-T91 with the Kim-Park separation. FPRD-T165 fixes the reversal orientation: their language C is the stationary-transport-hard projection outside SCA, while L=C^R is the PEG-hard projection outside PEG. The existing positive allocator and cover theorems remain valid for their stated subclasses.

Open work

Add the exact primary-source locator and keep source verification separate from proof of the FPRD consequence.

Notes

FPRD-T164 closes the former open target by composing FPRD-T91 with the Kim-Park separation. FPRD-T165 fixes the reversal orientation: their language C is the stationary-transport-hard projection outside SCA, while L=C^R is the PEG-hard projection outside PEG. The existing positive allocator and cover theorems remain valid for their stated subclasses.