Round 2 verification audit for C019
Model: gpt-5
Claim: The singlet fidelity is estimated from measured spin correlators via F(|Psi^->) = (1/4)(1 -
Source alignment: source/main.tex:124-125 (Experiment)
Prior official verdict: verified with failure_reason None.
Executable evidence: sympy_check.py. Sandbox rerun logs: sympy_check.log.
Independent audit: I scanned the copied script for imports/shared helper dependencies and reran it through the sandbox. The code is self-contained in this attempt directory and targets the claim strategy: Expand the projector |Psi^-><Psi^-| in the Pauli basis and confirm it equals (1/4)(I - XX - YY - ZZ).. I checked the relevant family model rather than relying only on exit status; the rerun is treated as one reproducibility input.
Decision:
Round 2 verdict is verified with failure_reason None and limitations []. Notes: Exact identity |Psi-><Psi-|=(1/4)(I-XX-YY-ZZ) verified (sympy); thus F=(1/4)(1-