{"abstract":"Encoder phase state tracks the wrong half-cell.","category":"PCM sample encoding","checks":8,"contract":"Encode PCM transport payload bits as stipulated biphase-mark half-cells with mandatory boundary transitions and explicit initial/final physical levels.","contract_signature":"bits, initial","evaluation_group":"s3-pcm-pcm-biphase-mark-generation","failed_approach":"Storing logical payload rather than physical level corrupts following transitions.","family":"s3-pcm-pcm-biphase-mark-generation-previous-cell-state","id":"FA-50256","implementations":{"attempt":{"sha256":"7119ee219980b486123d38e68150c95778e7404066f9308711e686ff5d57ec42","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(bits, initial):\n    previous=initial\n    cells=[]\n    for bit in bits:\n        first=1-previous\n        second=1-first if bit else first\n        cells.append([first,second])\n        previous=bit\n    return [cells,previous]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([0, 1, 0, 1], 0)), [[[1, 1], [0, 1], [0, 0], [1, 0]], 0])\ncheck('oracle 2', solve(*([1, 1, 1], 1)), [[[0, 1], [0, 1], [0, 1]], 1])\ncheck('oracle 3', solve(*([0, 0], 0)), [[[1, 1], [0, 0]], 0])\ncheck('oracle 4', solve(*([], 1)), [[], 1])\ncheck('oracle 5', solve(*([1], 0)), [[[1, 0]], 0])\ncheck('oracle 6', solve(*([0, 1, 1, 0], 1)), [[[0, 0], [1, 0], [1, 0], [1, 1]], 1])\ncheck('oracle 7', solve(*([0], 1)), [[[0, 0]], 0])\nif N == 1: check('variant packet 1', solve(*[[0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 2: check('variant packet 2', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 3: check('variant packet 3', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 4: check('variant packet 4', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 5: check('variant packet 5', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"aa78931058275f622d9e1ad600bfdaa77a3e7c37a824252ff03b4334e76d8a7a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(bits, initial):\n    previous=initial\n    cells=[]\n    for bit in bits:\n        first=1-previous\n        second=1-first if bit else first\n        cells.append([first,second])\n        previous=first\n    return [cells,previous]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([0, 1, 0, 1], 0)), [[[1, 1], [0, 1], [0, 0], [1, 0]], 0])\ncheck('oracle 2', solve(*([1, 1, 1], 1)), [[[0, 1], [0, 1], [0, 1]], 1])\ncheck('oracle 3', solve(*([0, 0], 0)), [[[1, 1], [0, 0]], 0])\ncheck('oracle 4', solve(*([], 1)), [[], 1])\ncheck('oracle 5', solve(*([1], 0)), [[[1, 0]], 0])\ncheck('oracle 6', solve(*([0, 1, 1, 0], 1)), [[[0, 0], [1, 0], [1, 0], [1, 1]], 1])\ncheck('oracle 7', solve(*([0], 1)), [[[0, 0]], 0])\nif N == 1: check('variant packet 1', solve(*[[0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 2: check('variant packet 2', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 3: check('variant packet 3', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 4: check('variant packet 4', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nif N == 5: check('variant packet 5', solve(*[[0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1], 0]), [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Stipulated finite model; no claim of hardware timing or full file-format conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"s3-pcm-pcm-biphase-mark-generation-previous-cell-state","generated_at":"2026-09-29T14:45:07.502547+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline PCM interchange uses these exact bounded packet and sample representation decisions.","root_cause":"Encoder phase state tracks the wrong half-cell.","sha256":"6179e934344fd7598e1e8023398cb4b6c35f664d9eaadeb071e2e8c08aefe901","title":"Pcm biphase mark generation: previous cell state · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":42.719,"exit_code":1,"observations":[{"actual":[[[1,1],[1,0],[0,0],[1,0]],1],"check":"oracle 1","expected":[[[1,1],[0,1],[0,0],[1,0]],0],"passed":false},{"actual":[[[0,1],[0,1],[0,1]],1],"check":"oracle 2","expected":[[[0,1],[0,1],[0,1]],1],"passed":true},{"actual":[[[1,1],[1,1]],0],"check":"oracle 3","expected":[[[1,1],[0,0]],0],"passed":false},{"actual":[[],1],"check":"oracle 4","expected":[[],1],"passed":true},{"actual":[[[1,0]],1],"check":"oracle 5","expected":[[[1,0]],0],"passed":false},{"actual":[[[0,0],[1,0],[0,1],[0,0]],0],"check":"oracle 6","expected":[[[0,0],[1,0],[1,0],[1,1]],1],"passed":false},{"actual":[[[0,0]],0],"check":"oracle 7","expected":[[[0,0]],0],"passed":true},{"actual":[[[1,1],[1,0],[0,0],[1,0],[0,0],[1,0],[0,0],[1,0]],1],"check":"variant packet 1","expected":[[[1,1],[0,1],[0,0],[1,0],[1,1],[0,1],[0,0],[1,0]],0],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[[1, 1], [1, 0], [0, 0], [1, 0]], 1], \"expected\": [[[1, 1], [0, 1], [0, 0], [1, 0]], 0], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[[0, 1], [0, 1], [0, 1]], 1], \"expected\": [[[0, 1], [0, 1], [0, 1]], 1], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [[[1, 1], [1, 1]], 0], \"expected\": [[[1, 1], [0, 0]], 0], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [[], 1], \"expected\": [[], 1], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[[1, 0]], 1], \"expected\": [[[1, 0]], 0], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[[0, 0], [1, 0], [0, 1], [0, 0]], 0], \"expected\": [[[0, 0], [1, 0], [1, 0], [1, 1]], 1], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[[0, 0]], 0], \"expected\": [[[0, 0]], 0], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [[[1, 1], [1, 0], [0, 0], [1, 0], [0, 0], [1, 0], [0, 0], [1, 0]], 1], \"expected\": [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.908,"exit_code":1,"observations":[{"actual":[[[1,1],[0,1],[1,1],[0,1]],0],"check":"oracle 1","expected":[[[1,1],[0,1],[0,0],[1,0]],0],"passed":false},{"actual":[[[0,1],[1,0],[0,1]],0],"check":"oracle 2","expected":[[[0,1],[0,1],[0,1]],1],"passed":false},{"actual":[[[1,1],[0,0]],0],"check":"oracle 3","expected":[[[1,1],[0,0]],0],"passed":true},{"actual":[[],1],"check":"oracle 4","expected":[[],1],"passed":true},{"actual":[[[1,0]],1],"check":"oracle 5","expected":[[[1,0]],0],"passed":false},{"actual":[[[0,0],[1,0],[0,1],[1,1]],1],"check":"oracle 6","expected":[[[0,0],[1,0],[1,0],[1,1]],1],"passed":false},{"actual":[[[0,0]],0],"check":"oracle 7","expected":[[[0,0]],0],"passed":true},{"actual":[[[1,1],[0,1],[1,1],[0,1],[1,1],[0,1],[1,1],[0,1]],0],"check":"variant packet 1","expected":[[[1,1],[0,1],[0,0],[1,0],[1,1],[0,1],[0,0],[1,0]],0],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[[1, 1], [0, 1], [1, 1], [0, 1]], 0], \"expected\": [[[1, 1], [0, 1], [0, 0], [1, 0]], 0], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[[0, 1], [1, 0], [0, 1]], 0], \"expected\": [[[0, 1], [0, 1], [0, 1]], 1], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [[[1, 1], [0, 0]], 0], \"expected\": [[[1, 1], [0, 0]], 0], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [[], 1], \"expected\": [[], 1], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[[1, 0]], 1], \"expected\": [[[1, 0]], 0], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[[0, 0], [1, 0], [0, 1], [1, 1]], 1], \"expected\": [[[0, 0], [1, 0], [1, 0], [1, 1]], 1], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [[[0, 0]], 0], \"expected\": [[[0, 0]], 0], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [[[1, 1], [0, 1], [1, 1], [0, 1], [1, 1], [0, 1], [1, 1], [0, 1]], 0], \"expected\": [[[1, 1], [0, 1], [0, 0], [1, 0], [1, 1], [0, 1], [0, 0], [1, 0]], 0], \"passed\": false}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}