GATE D0
Tight-class analytic bridge
What changed
Reconstructed the polynomial-method core, isolated the load-bearing Fermat-indicator step, localized why it needs k+1 prime. The obstruction for k+1=14 is algebraic.
Evidence
check 1Polynomial proposition verified exhaustively for odd-prime moduli
check 2Fermat-indicator lemma exact for primes, fails for composites
check 3Proposition numbering resolved against the source paper
Verification: single · I2 · 7 artifacts (reports, verifiers, corruption suites, manifest with SHA-256)