{"abstract":"Sequence-level labels are taken from the first token.","category":"Training label alignment","checks":7,"contract":"For each sequence of token class IDs, return its most frequent class; ties choose the numerically smallest class. Empty sequences return -1.","contract_signature":"sequences","evaluation_group":"training-label-alignment-majority-sequence-label","failed_approach":"Choosing the most frequent class repairs aggregation but breaks the specified smallest-class tie rule.","family":"w3-training-label-alignment-sequence-example-label-reduce","id":"FA-98016","implementations":{"attempt":{"sha256":"63536c4e4980f2277f2399eeaf5e131bc2d038f1a1b6a41958c4cc642b1f37bb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(sequences):\n    return [max(set(x),key=lambda y:(x.count(y),y)) if x else -1 for x in sequences]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('majority differs first',solve([[1,2,2]]),[2])\ncheck('tie smallest',solve([[N,N+1]]),[N])\ncheck('empty sequence',solve([[]]),[-1])\ncheck('empty batch',solve([]),[])\ncheck('singleton',solve([[N]]),[N])\ncheck('later class wins',solve([[0,1,1,2,1]]),[1])\ncheck('negative classes',solve([[-2,-1,-2]]),[-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":"af293d42e9c1cf72b6c92e04e5724a8b3a374edcfe5d4ebdc56027549216024f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(sequences):\n    return [x[0] if x else -1 for x in sequences]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('majority differs first',solve([[1,2,2]]),[2])\ncheck('tie smallest',solve([[N,N+1]]),[N])\ncheck('empty sequence',solve([[]]),[-1])\ncheck('empty batch',solve([]),[])\ncheck('singleton',solve([[N]]),[N])\ncheck('later class wins',solve([[0,1,1,2,1]]),[1])\ncheck('negative classes',solve([[-2,-1,-2]]),[-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":"Token labels are integers; majority ties use ascending numeric order. 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-training-label-alignment-sequence-example-label-reduce","generated_at":"2026-09-30T16:48:08.407844+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small deterministic training-data operation makes label ownership and ordering explicit.","root_cause":"The reducer assumes the first token carries the sequence-level class.","sha256":"3d08867b13fc63888f4750db8ce99c5046f8c44ac3a3c34abb7baee52c86095f","title":"Sequence-level labels are taken from the first token · 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":28.075,"exit_code":1,"observations":[{"actual":[2],"check":"majority differs first","expected":[2],"passed":true},{"actual":[2],"check":"tie smallest","expected":[1],"passed":false},{"actual":[-1],"check":"empty sequence","expected":[-1],"passed":true},{"actual":[],"check":"empty batch","expected":[],"passed":true},{"actual":[1],"check":"singleton","expected":[1],"passed":true},{"actual":[1],"check":"later class wins","expected":[1],"passed":true},{"actual":[-2],"check":"negative classes","expected":[-2],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"majority differs first\", \"actual\": [2], \"expected\": [2], \"passed\": true}, {\"check\": \"tie smallest\", \"actual\": [2], \"expected\": [1], \"passed\": false}, {\"check\": \"empty sequence\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"empty batch\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"later class wins\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"negative classes\", \"actual\": [-2], \"expected\": [-2], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":26.457,"exit_code":1,"observations":[{"actual":[1],"check":"majority differs first","expected":[2],"passed":false},{"actual":[1],"check":"tie smallest","expected":[1],"passed":true},{"actual":[-1],"check":"empty sequence","expected":[-1],"passed":true},{"actual":[],"check":"empty batch","expected":[],"passed":true},{"actual":[1],"check":"singleton","expected":[1],"passed":true},{"actual":[0],"check":"later class wins","expected":[1],"passed":false},{"actual":[-2],"check":"negative classes","expected":[-2],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"majority differs first\", \"actual\": [1], \"expected\": [2], \"passed\": false}, {\"check\": \"tie smallest\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"empty sequence\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"empty batch\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"later class wins\", \"actual\": [0], \"expected\": [1], \"passed\": false}, {\"check\": \"negative classes\", \"actual\": [-2], \"expected\": [-2], \"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."}}