{"abstract":"different-length fingerprints appear identical.","category":"Dataset deduplication grouping","checks":6,"contract":"Return Hamming distance for equal-length strings; return None for unequal lengths.","contract_signature":"a, b","evaluation_group":"dedup-hamming-length","failed_approach":"Padding both strings with the same sentinel can hide genuine suffix differences.","family":"w3-dataset-deduplication-grouping-hamming-length-check","id":"FA-100296","implementations":{"attempt":{"sha256":"c6ae2a71533656d63ba7ab8cbe68fe82a39524e8766e4f00da05d11e9ba1851a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(a, b):\n    m=max(len(a),len(b)); return sum((a+\"\\0\"*m)[i]!=(b+\"\\0\"*m)[i] for i in range(m))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('one mismatch',solve('abc','a'+str(N%10)+'c'),1 if str(N%10)!='b' else 0)\ncheck('equal strings',solve('x'*N,'x'*N),0)\ncheck('unequal suffix',solve('a','ab'),None)\ncheck('empty equal',solve('',''),0)\ncheck('empty versus nonempty',solve('','x'),None)\ncheck('multiple mismatches',solve('abcd','wxyz'),4)\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":"6b6fb88283aeb33bc21edc6cd7162d18e2383b0261478cab7ff30ea872ea720c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(a, b):\n    return sum(x!=y for x,y in zip(a,b))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('one mismatch',solve('abc','a'+str(N%10)+'c'),1 if str(N%10)!='b' else 0)\ncheck('equal strings',solve('x'*N,'x'*N),0)\ncheck('unequal suffix',solve('a','ab'),None)\ncheck('empty equal',solve('',''),0)\ncheck('empty versus nonempty',solve('','x'),None)\ncheck('multiple mismatches',solve('abcd','wxyz'),4)\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-hamming-length-check","generated_at":"2026-09-30T16:48:34.014166+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 distance loop stops at the shorter fingerprint and ignores suffix symbols.","sha256":"6fbe079369c728fc0ceb47eb392be86d19109ca90db2e835328283b7a50b0802","title":"Dataset deduplication: different-length fingerprints appear identical · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":29.913,"exit_code":1,"observations":[{"actual":1,"check":"one mismatch","expected":1,"passed":true},{"actual":0,"check":"equal strings","expected":0,"passed":true},{"actual":1,"check":"unequal suffix","expected":null,"passed":false},{"actual":0,"check":"empty equal","expected":0,"passed":true},{"actual":1,"check":"empty versus nonempty","expected":null,"passed":false},{"actual":4,"check":"multiple mismatches","expected":4,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"one mismatch\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"equal strings\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"unequal suffix\", \"actual\": 1, \"expected\": null, \"passed\": false}, {\"check\": \"empty equal\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"empty versus nonempty\", \"actual\": 1, \"expected\": null, \"passed\": false}, {\"check\": \"multiple mismatches\", \"actual\": 4, \"expected\": 4, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":29.24,"exit_code":1,"observations":[{"actual":1,"check":"one mismatch","expected":1,"passed":true},{"actual":0,"check":"equal strings","expected":0,"passed":true},{"actual":0,"check":"unequal suffix","expected":null,"passed":false},{"actual":0,"check":"empty equal","expected":0,"passed":true},{"actual":0,"check":"empty versus nonempty","expected":null,"passed":false},{"actual":4,"check":"multiple mismatches","expected":4,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"one mismatch\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"equal strings\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"unequal suffix\", \"actual\": 0, \"expected\": null, \"passed\": false}, {\"check\": \"empty equal\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"empty versus nonempty\", \"actual\": 0, \"expected\": null, \"passed\": false}, {\"check\": \"multiple mismatches\", \"actual\": 4, \"expected\": 4, \"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."}}