{"abstract":"The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.","category":"Iterator consumption","checks":4,"contract":"Retain values unequal to the sentinel, including other falsy values. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","contract_signature":"x, y=None","evaluation_group":"model-b42122b441420f1a","failed_approach":"A truthiness condition rejects valid falsy values unrelated to the sentinel.","family":"xr-filterfalse-inverts-predicate","id":"FA-4556","implementations":{"attempt":{"sha256":"72891d0b09686d1638e44f4fd989acaf5633e5d3ccb180a4f2315724f2b3d6d5","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 [v for v in x if v and v!=y]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('sentinel removed', solve(['a', 's', 'b'], 's'), ['a', 'b'])\ncheck('falsy retained', solve([None, 's', ''], 's'), [None, ''])\ncheck('all removed', solve(['s', 's'], 's'), [])\ncheck('empty', solve([], 's'), [])\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":"ff1d0139553cf3e76f2279d6feba937f4f1be8d0934257d744829a05f8736fc6","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(filter(lambda v:v==y,x))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('sentinel removed', solve(['a', 's', 'b'], 's'), ['a', 'b'])\ncheck('falsy retained', solve([None, 's', ''], 's'), [None, ''])\ncheck('all removed', solve(['s', 's'], 's'), [])\ncheck('empty', solve([], 's'), [])\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-filterfalse-inverts-predicate","generated_at":"2026-09-29T14:37:40.530037+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":"The predicate is used directly rather than inverted.","sha256":"b6fa90502d8eb34acd738ba0f4c7a4a4274e08360b7aaa68f566c7988d7c40a1","title":"Filterfalse inverts predicate · 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":40.119,"exit_code":1,"observations":[{"actual":["a","b"],"check":"sentinel removed","expected":["a","b"],"passed":true},{"actual":[],"check":"falsy retained","expected":[null,""],"passed":false},{"actual":[],"check":"all removed","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"sentinel removed\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"b\"], \"passed\": true}, {\"check\": \"falsy retained\", \"actual\": [], \"expected\": [null, \"\"], \"passed\": false}, {\"check\": \"all removed\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":114.349,"exit_code":1,"observations":[{"actual":["s"],"check":"sentinel removed","expected":["a","b"],"passed":false},{"actual":["s"],"check":"falsy retained","expected":[null,""],"passed":false},{"actual":["s","s"],"check":"all removed","expected":[],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"sentinel removed\", \"actual\": [\"s\"], \"expected\": [\"a\", \"b\"], \"passed\": false}, {\"check\": \"falsy retained\", \"actual\": [\"s\"], \"expected\": [null, \"\"], \"passed\": false}, {\"check\": \"all removed\", \"actual\": [\"s\", \"s\"], \"expected\": [], \"passed\": false}, {\"check\": \"empty\", \"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."}}