{"abstract":"The operation returns a result or retained state that violates this contract: Return length-r combinations with replacement, allowing the same input position repeatedly.","category":"Iterator consumption","checks":4,"contract":"Return length-r combinations with replacement, allowing the same input position repeatedly. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","contract_signature":"x, y=None","evaluation_group":"model-a844499a985b7b02","failed_approach":"Cartesian products include decreasing positional orderings that combinations exclude.","family":"xr-combinations-with-replacement-allows-reused-position","id":"FA-4606","implementations":{"attempt":{"sha256":"f4855b9565ddc6a347a0042a1ba05607086ea8aabba7ce25e0b66e68ca2d6847","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport itertools as it\nfrom collections import deque\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [list(v) for v in it.product(x,repeat=y)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('repeat position', solve(['a', 'b'], 2), [['a', 'a'], ['a', 'b'], ['b', 'b']])\ncheck('one position reused', solve(['a'], 3), [['a', 'a', 'a']])\ncheck('zero choice', solve([], 0), [[]])\ncheck('empty positive choice', solve([], 2), [])\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":"e3edd7cd0e17345426c46a9cb69b2e7d277d5e92a07299329395bdcbf975c4db","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport itertools as it\nfrom collections import deque\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [list(v) for v in it.combinations(x,y)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('repeat position', solve(['a', 'b'], 2), [['a', 'a'], ['a', 'b'], ['b', 'b']])\ncheck('one position reused', solve(['a'], 3), [['a', 'a', 'a']])\ncheck('zero choice', solve([], 0), [[]])\ncheck('empty positive choice', solve([], 2), [])\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":"xr-combinations-with-replacement-allows-reused-position","generated_at":"2026-09-29T14:37:40.847198+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.","root_cause":"Ordinary combinations forbid reusing a source position.","sha256":"d6faa8fc6f71c656df4d55b34be4c57f80e41c4570afec95c902b9aa6af7c3cc","title":"Combinations with replacement allows reused position · case 01","variant":1,"variant_policy":"Five execution reruns of a fixed adversarial fixture suite; variant number does not alter semantic inputs.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":121.178,"exit_code":1,"observations":[{"actual":[["a","a"],["a","b"],["b","a"],["b","b"]],"check":"repeat position","expected":[["a","a"],["a","b"],["b","b"]],"passed":false},{"actual":[["a","a","a"]],"check":"one position reused","expected":[["a","a","a"]],"passed":true},{"actual":[[]],"check":"zero choice","expected":[[]],"passed":true},{"actual":[],"check":"empty positive choice","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"repeat position\", \"actual\": [[\"a\", \"a\"], [\"a\", \"b\"], [\"b\", \"a\"], [\"b\", \"b\"]], \"expected\": [[\"a\", \"a\"], [\"a\", \"b\"], [\"b\", \"b\"]], \"passed\": false}, {\"check\": \"one position reused\", \"actual\": [[\"a\", \"a\", \"a\"]], \"expected\": [[\"a\", \"a\", \"a\"]], \"passed\": true}, {\"check\": \"zero choice\", \"actual\": [[]], \"expected\": [[]], \"passed\": true}, {\"check\": \"empty positive choice\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.036,"exit_code":1,"observations":[{"actual":[["a","b"]],"check":"repeat position","expected":[["a","a"],["a","b"],["b","b"]],"passed":false},{"actual":[],"check":"one position reused","expected":[["a","a","a"]],"passed":false},{"actual":[[]],"check":"zero choice","expected":[[]],"passed":true},{"actual":[],"check":"empty positive choice","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"repeat position\", \"actual\": [[\"a\", \"b\"]], \"expected\": [[\"a\", \"a\"], [\"a\", \"b\"], [\"b\", \"b\"]], \"passed\": false}, {\"check\": \"one position reused\", \"actual\": [], \"expected\": [[\"a\", \"a\", \"a\"]], \"passed\": false}, {\"check\": \"zero choice\", \"actual\": [[]], \"expected\": [[]], \"passed\": true}, {\"check\": \"empty positive choice\", \"actual\": [], \"expected\": [], \"passed\": true}], \"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."}}