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188, 191, 198, 201, 239, 278, 294, 296, 298, 301, 307 ], "witness_provenance": { "found_by": [ "@vprusso" ], "date": "2026-09-27", "found_at_samples": 300000000, "tool": "verify/ris_gpu.py (build/ris_gpu, NVIDIA A40)", "seeds": [ 1209549509 ], "survived_samples": 300000000 } }, "Z": { "value": 28, "confidence": "upper_bound", "witness": [ 8, 16, 18, 22, 28, 29, 62, 70, 72, 76, 110, 122, 128, 138, 144, 146, 148, 149, 158, 167, 175, 190, 192, 224, 254, 262, 270, 303 ], "witness_provenance": { "found_by": [ "@vprusso" ], "date": "2026-09-27", "found_at_samples": 300000000, "tool": "verify/ris_gpu.py (build/ris_gpu, NVIDIA A40)", "seeds": [ 1209549509 ], "survived_samples": 300000000 } } }, "provenance": { "authors": [ "@vprusso" ], "model": "Claude Fable 5.1 (Claude Code)", "construction": "Periodic bivariate-bicycle code on Z_77 x Z_2 (n = 2*l*m = 308): x = S_77 tensor I_2, y = I_77 tensor S_2 (cyclic shifts), qubit index i*m + j in each block; A = x^0y^0 + x^27y^0 + x^36y^0 + x^39y^0, B = x^0y^0 + x^19y^0 + x^36y^0 + x^44y^1; H_X = [A|B], H_Z = [B^T|A^T] (research/kit/bb.py build_bb(77, 2, [[0, 0], [27, 0], [36, 0], [39, 0]], [[0, 0], [19, 0], [36, 0], [44, 1]])). gcd(77, 2) = 1, so Z_77 x Z_2 is cyclic of order 154 and the code is the cyclic generalized-bicycle code over Z_154 with a(z) = z^0 + z^36 + z^104 + z^116, b(z) = z^0 + z^36 + z^96 + z^121 (CRT relabeling x^a y^b -> z^t, t = a mod 77, t = b mod 2).", "date": "2026-09-27" } }