{"abstract":"near-duplicate score ignores unmatched token union.","category":"Dataset deduplication grouping","checks":6,"contract":"Return Jaccard similarity of token sets; two empty sets score 1.","contract_signature":"a, b","evaluation_group":"dedup-jaccard-score","failed_approach":"Using the larger set size as denominator overstates partial overlap compared with union normalization.","family":"w3-dataset-deduplication-grouping-jaccard-union-denominator","id":"FA-100286","implementations":{"attempt":{"sha256":"33cfe76e969bef5ecc835c1a3adb6a1b91cb3ee0c27461c4f6a24087f5a799ee","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(a, b):\n    return len(set(a)&set(b))/max(len(set(a)),len(set(b))) if set(a) or set(b) else 1\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('balanced overlap',solve(['a','b'],['a','c']),1/3)\ncheck('left containment',solve(['a'],['a','b']),0.5)\ncheck('right containment',solve(['a','b'],['a']),0.5)\ncheck('disjoint',solve(['a'],['b']),0)\ncheck('both empty',solve([],[]),1)\ncheck('duplicates ignored',solve(['a','a','b'],['a','b','b']),1)\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":"6e01d4d18fe73cd6146b59cea0999e1e080460c8576e8e3737dff9a60e2724b4","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(a, b):\n    return len(set(a)&set(b))/len(set(a)) if a else (1 if not b else 0)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('balanced overlap',solve(['a','b'],['a','c']),1/3)\ncheck('left containment',solve(['a'],['a','b']),0.5)\ncheck('right containment',solve(['a','b'],['a']),0.5)\ncheck('disjoint',solve(['a'],['b']),0)\ncheck('both empty',solve([],[]),1)\ncheck('duplicates ignored',solve(['a','a','b'],['a','b','b']),1)\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":"Inputs are small in-memory fixtures with the stated contract; results do not claim production deduplication quality. 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":"w3-dataset-deduplication-grouping-jaccard-union-denominator","generated_at":"2026-09-30T16:48:34.014225+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic toy operation makes one dataset equivalence or representative rule explicit.","root_cause":"The overlap ratio is normalized by the left document size only.","sha256":"8547597cac5038c83fea22381fe19780c4a691dc1a1479303477ad0ca362352d","title":"Dataset deduplication: near-duplicate score ignores unmatched token union · case 01","variant":1,"variant_policy":"The same explicitly authored fixtures repeat across all five numbered records; runtime N is unused. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":30.23,"exit_code":1,"observations":[{"actual":0.5,"check":"balanced overlap","expected":0.3333333333333333,"passed":false},{"actual":0.5,"check":"left containment","expected":0.5,"passed":true},{"actual":0.5,"check":"right containment","expected":0.5,"passed":true},{"actual":0.0,"check":"disjoint","expected":0,"passed":true},{"actual":1,"check":"both empty","expected":1,"passed":true},{"actual":1.0,"check":"duplicates ignored","expected":1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"balanced overlap\", \"actual\": 0.5, \"expected\": 0.3333333333333333, \"passed\": false}, {\"check\": \"left containment\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"right containment\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"disjoint\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"both empty\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"duplicates ignored\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.539,"exit_code":1,"observations":[{"actual":0.5,"check":"balanced overlap","expected":0.3333333333333333,"passed":false},{"actual":1.0,"check":"left containment","expected":0.5,"passed":false},{"actual":0.5,"check":"right containment","expected":0.5,"passed":true},{"actual":0.0,"check":"disjoint","expected":0,"passed":true},{"actual":1,"check":"both empty","expected":1,"passed":true},{"actual":1.0,"check":"duplicates ignored","expected":1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"balanced overlap\", \"actual\": 0.5, \"expected\": 0.3333333333333333, \"passed\": false}, {\"check\": \"left containment\", \"actual\": 1.0, \"expected\": 0.5, \"passed\": false}, {\"check\": \"right containment\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"disjoint\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"both empty\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"duplicates ignored\", \"actual\": 1.0, \"expected\": 1, \"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."}}