A Three-Layer Obstruction for Uniformly Popular Differences — v0.1.0-candidate

Release notes — v0.1.0-candidate

Version DOI: 10.5281/zenodo.22161245.

This anonymous, unrefereed candidate records:

• an explicit counterexample in Z/21Z to the strict one-third question in
  AIM Problem 1.18;
• a three-layer construction with minimum difference multiplicity
  min(h, 2m); and
• odd-cyclic counterexamples for every fixed threshold below 2/5.

The release does not claim sufficiency or sharpness at 2/5, minimality of
the C21 witness, novelty, priority, independent reproduction, formal
verification, external specialist review, or journal peer review.

Producer-side Python, optimized-Python, JavaScript and semantic-mutation checks
pass. The five-role editorial round and confirmation report are internal and
correlated with the producing workflow.