{"abstract":"Parallel twelfths (G5 over C4 moving to A5 over D4) and parallel double octaves are not reported.","category":"Music interval and transposition theory","checks":8,"contract":"Input [upper, lower], equal-length lists of MIDI pitches. For each adjacent pair of positions i, i+1 report [i, \"P5\"] or [i, \"P8\"] when the interval (upper - lower) mod 12 is 7 or 0 at both positions (the same class), both voices move (no repeated note in either), and they move in the same direction. Return the list in order; unequal lengths return None.","contract_signature":"x","evaluation_group":"w2-music-interval-parallel-perfects","failed_approach":"Reducing the absolute difference also reports crossed voices a fourth apart as parallel fifths.","family":"w2-music-interval-parallel-perfects-compound-reduction","id":"FA-81201","implementations":{"attempt":{"sha256":"4128b1c0bbb7f69a2eec3bec8e6cb34d85d0672aa75cca891609f8c824044b20","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 2:\n        return None\n    up, lo = x\n    if len(up) != len(lo):\n        return None\n    out = []\n    for i in range(len(up) - 1):\n        a = abs(up[i] - lo[i]) % 12\n        b = abs(up[i + 1] - lo[i + 1]) % 12\n        mu = up[i + 1] - up[i]\n        ml = lo[i + 1] - lo[i]\n        if a != b or a not in (0, 7):\n            continue\n        if mu == 0 or ml == 0:\n            continue\n        if (mu > 0) != (ml > 0):\n            continue\n        out.append([i, 'P8' if a == 0 else 'P5'])\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([[67, 69], [60, 62]], [[0, 'P5']]), ([[72, 74], [60, 62]], [[0, 'P8']]), ([[67, 67], [60, 60]], []), ([[67, 69], [60, 60]], []), ([[72, 67], [60, 72]], []), ([[72, 79], [60, 55]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']])], [([[79, 81], [60, 62]], [[0, 'P5']]), ([[72, 67], [60, 72]], []), ([[72, 79], [60, 55]], []), ([[67, 72], [60, 65]], [[0, 'P5']]), ([[72, 79], [60, 60]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[72, 72, 74], [60, 60, 62]], [[1, 'P8']])], [([[72, 79], [60, 60]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[67, 69, 71], [60, 62, 64]], [[0, 'P5'], [1, 'P5']]), ([[67, 65], [60, 58]], [[0, 'P5']]), ([[67, 72], [60, 60]], []), ([[64, 65], [60, 62]], []), ([[76, 74], [64, 62]], [[0, 'P8']])], [([[72, 74], [60, 62]], [[0, 'P8']]), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[72, 72, 74], [60, 60, 62]], [[1, 'P8']]), ([[67, 72], [60, 60]], []), ([[64, 65], [60, 62]], []), ([[67], [60]], []), ([[], []], [])], [([[79, 81], [60, 62]], [[0, 'P5']]), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[], []], []), ([[67, 69], [60]], None), ([[76, 74], [64, 62]], [[0, 'P8']]), ([[67, 71], [60, 64]], [[0, 'P5']]), ([[79, 74], [60, 67]], [])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, solve(args), expected)\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":"6ddacf52d692515789b654b2ea296ff83d085fe6b96bb0b048e59bb113b0985d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 2:\n        return None\n    up, lo = x\n    if len(up) != len(lo):\n        return None\n    out = []\n    for i in range(len(up) - 1):\n        a = up[i] - lo[i]\n        b = up[i + 1] - lo[i + 1]\n        mu = up[i + 1] - up[i]\n        ml = lo[i + 1] - lo[i]\n        if a != b or a not in (0, 7):\n            continue\n        if mu == 0 or ml == 0:\n            continue\n        if (mu > 0) != (ml > 0):\n            continue\n        out.append([i, 'P8' if a == 0 else 'P5'])\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([[67, 69], [60, 62]], [[0, 'P5']]), ([[72, 74], [60, 62]], [[0, 'P8']]), ([[67, 67], [60, 60]], []), ([[67, 69], [60, 60]], []), ([[72, 67], [60, 72]], []), ([[72, 79], [60, 55]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']])], [([[79, 81], [60, 62]], [[0, 'P5']]), ([[72, 67], [60, 72]], []), ([[72, 79], [60, 55]], []), ([[67, 72], [60, 65]], [[0, 'P5']]), ([[72, 79], [60, 60]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[72, 72, 74], [60, 60, 62]], [[1, 'P8']])], [([[72, 79], [60, 60]], []), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[67, 69, 71], [60, 62, 64]], [[0, 'P5'], [1, 'P5']]), ([[67, 65], [60, 58]], [[0, 'P5']]), ([[67, 72], [60, 60]], []), ([[64, 65], [60, 62]], []), ([[76, 74], [64, 62]], [[0, 'P8']])], [([[72, 74], [60, 62]], [[0, 'P8']]), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[72, 72, 74], [60, 60, 62]], [[1, 'P8']]), ([[67, 72], [60, 60]], []), ([[64, 65], [60, 62]], []), ([[67], [60]], []), ([[], []], [])], [([[79, 81], [60, 62]], [[0, 'P5']]), ([[60, 62], [67, 69]], []), ([[55, 57], [60, 62]], [[0, 'P5']]), ([[], []], []), ([[67, 69], [60]], None), ([[76, 74], [64, 62]], [[0, 'P8']]), ([[67, 71], [60, 64]], [[0, 'P5']]), ([[79, 74], [60, 67]], [])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, solve(args), expected)\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":"A deterministic bounded teaching model with a stipulated toy contract; it is not a complete music notation or theory engine. 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":"w2-music-interval-parallel-perfects-compound-reduction","generated_at":"2026-09-29T14:50:00.765563+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Counterpoint checkers and voice-leading validators flag forbidden parallel perfect intervals.","root_cause":"The interval class is taken from the raw semitone difference without reducing compounds modulo twelve.","sha256":"77262ca0d0f6ac9db6c320952d4293dc3a1f19c5967dcc97a669222c602e0def","title":"Parallel fifths and octaves between two voices: compound fifths and octaves missed · 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":38.717,"exit_code":1,"observations":[{"actual":[[0,"P5"]],"check":"oracle 0","expected":[[0,"P5"]],"passed":true},{"actual":[[0,"P8"]],"check":"oracle 1","expected":[[0,"P8"]],"passed":true},{"actual":[],"check":"oracle 2","expected":[],"passed":true},{"actual":[],"check":"oracle 3","expected":[],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[],"check":"oracle 5","expected":[],"passed":true},{"actual":[[0,"P5"]],"check":"oracle 6","expected":[],"passed":false},{"actual":[],"check":"oracle 7","expected":[[0,"P5"]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [[0, \"P5\"]], \"expected\": [[0, \"P5\"]], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [[0, \"P8\"]], \"expected\": [[0, \"P8\"]], \"passed\": true}, {\"check\": \"oracle 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [[0, \"P5\"]], \"expected\": [], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [], \"expected\": [[0, \"P5\"]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.376,"exit_code":1,"observations":[{"actual":[[0,"P5"]],"check":"oracle 0","expected":[[0,"P5"]],"passed":true},{"actual":[],"check":"oracle 1","expected":[[0,"P8"]],"passed":false},{"actual":[],"check":"oracle 2","expected":[],"passed":true},{"actual":[],"check":"oracle 3","expected":[],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[],"check":"oracle 5","expected":[],"passed":true},{"actual":[],"check":"oracle 6","expected":[],"passed":true},{"actual":[],"check":"oracle 7","expected":[[0,"P5"]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [[0, \"P5\"]], \"expected\": [[0, \"P5\"]], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [], \"expected\": [[0, \"P8\"]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [], \"expected\": [[0, \"P5\"]], \"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."}}