{"abstract":"Colliding assignments remain in the sample count.","category":"Combinatorics","checks":4,"contract":"Nonnegative integer counts. Permutation and combination counts are zero when a requested selection exceeds the available objects. Shape sizes satisfy the preconditions stated below. Birthday distinct assignments. Exact operational definition: math.perm(days,people)","contract_signature":"people, days","evaluation_group":"model-1d553a726bcc9bd0","failed_approach":"People identities are lost by unordered day selection.","family":"xn-birthday-distinct-assignments","id":"FA-5706","implementations":{"attempt":{"sha256":"e8d3875bb0f07d98c2744b4e30f5964121cbc9b280207abe730b2beebeebf275","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(people, days):\n    return math.comb(days,people)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (2, 4)', solve(*(2, 4)), 12)\ncheck('fixture 2: (3, 3)', solve(*(3, 3)), 6)\ncheck('fixture 3: (0, 5)', solve(*(0, 5)), 1)\ncheck('fixture 4: (4, 3)', solve(*(4, 3)), 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":"2d939f356aec8210b970ed3ab81f3059267f0e2e5d6a7bc7a8d4370cbbd8bc90","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(people, days):\n    return days**people\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (2, 4)', solve(*(2, 4)), 12)\ncheck('fixture 2: (3, 3)', solve(*(3, 3)), 6)\ncheck('fixture 3: (0, 5)', solve(*(0, 5)), 1)\ncheck('fixture 4: (4, 3)', solve(*(4, 3)), 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":" 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":"xn-birthday-distinct-assignments","generated_at":"2026-09-29T14:37:52.803174+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Combinatorics results depend on the stated convention.","root_cause":"Colliding assignments remain in the sample count.","sha256":"20f9b21fd384a96a8b5aa67487a877b389699611ae6d5b866028d0a6fd8a077f","title":"Birthday distinct assignments · 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":58.613,"exit_code":1,"observations":[{"actual":6,"check":"fixture 1: (2, 4)","expected":12,"passed":false},{"actual":1,"check":"fixture 2: (3, 3)","expected":6,"passed":false},{"actual":1,"check":"fixture 3: (0, 5)","expected":1,"passed":true},{"actual":0,"check":"fixture 4: (4, 3)","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (2, 4)\", \"actual\": 6, \"expected\": 12, \"passed\": false}, {\"check\": \"fixture 2: (3, 3)\", \"actual\": 1, \"expected\": 6, \"passed\": false}, {\"check\": \"fixture 3: (0, 5)\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 4: (4, 3)\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":64.585,"exit_code":1,"observations":[{"actual":16,"check":"fixture 1: (2, 4)","expected":12,"passed":false},{"actual":27,"check":"fixture 2: (3, 3)","expected":6,"passed":false},{"actual":1,"check":"fixture 3: (0, 5)","expected":1,"passed":true},{"actual":81,"check":"fixture 4: (4, 3)","expected":0,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (2, 4)\", \"actual\": 16, \"expected\": 12, \"passed\": false}, {\"check\": \"fixture 2: (3, 3)\", \"actual\": 27, \"expected\": 6, \"passed\": false}, {\"check\": \"fixture 3: (0, 5)\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 4: (4, 3)\", \"actual\": 81, \"expected\": 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."}}