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 "provenance": {
  "authors": [
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  "construction": "Generalized-bicycle CSS code: circulant matrices A,B over F2[x]/(x^21-1), a=(0,1,3), b=(0,2,13), Hx=[A|B], Hz=[B^T|A^T]",
  "origin": "submission",
  "date": "2026-09-19",
  "model": "Claude Sonnet 5",
  "notes": "Shares [[42,6,6]] parameters with codes/42-6-6.json (@mathysrennela, 2D-local bilayer via simulated annealing over an integer grid). Confirmed NOT equivalent: this code has uniform check weight 6 and uniform qubit degree 6 throughout (expected for its algebraic circulant construction), while the existing entry has a mixed weight-3/4/5/6 and degree-3/4/5/6 distribution (expected for a geometrically-annealed layout). Row-weight and degree histograms are permutation invariants, so this rules out equivalence under any qubit/check relabeling."
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