{"abstract":"tied extrema are resolved by input order.","category":"Preference pair construction","checks":6,"contract":"Rows are [prompt,id,score]. Emit [prompt,best_id,worst_id] only when max and min are each unique; a middle tie is allowed.","contract_signature":"rows","evaluation_group":"preference-tie-skip-group-extrema","failed_approach":"Skipping every group containing any tie discards groups with a harmless middle tie.","family":"w3-preference-pair-construction-tie-skip-group-extrema","id":"FA-100091","implementations":{"attempt":{"sha256":"0a3662bf0da799750c2825d68ad37e67b59ed39697dca4ec7e5145597a69acc0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    groups={}\n    for r in rows: groups.setdefault(r[0],[]).append(r)\n    return [[p,max(g,key=lambda r:r[2])[1],min(g,key=lambda r:r[2])[1]] for p,g in groups.items() if len(g)>1 and len({x[2] for x in g})==len(g)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\np='p'+str(N)\ncheck('tied maximum skipped',solve([[p,'a',3],[p,'b',3],[p,'c',0]]),[])\ncheck('tied minimum skipped',solve([[p,'a',3],[p,'b',0],[p,'c',0]]),[])\ncheck('middle tie allowed',solve([[p,'a',3],[p,'b',2],[p,'c',2],[p,'d',0]]),[[p,'a','d']])\ncheck('unique extremes',solve([[p,'a',N],[p,'b',0]]),[[p,'a','b']])\ncheck('singleton',solve([[p,'a',N]]),[])\ncheck('empty',solve([]),[])\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":"0008d44d3919651ceb4cc88fd0240beaea886a358ad83abcd87019011b60c164","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    groups={}\n    for r in rows: groups.setdefault(r[0],[]).append(r)\n    return [[p,max(g,key=lambda r:r[2])[1],min(g,key=lambda r:r[2])[1]] for p,g in groups.items() if len(g)>1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\np='p'+str(N)\ncheck('tied maximum skipped',solve([[p,'a',3],[p,'b',3],[p,'c',0]]),[])\ncheck('tied minimum skipped',solve([[p,'a',3],[p,'b',0],[p,'c',0]]),[])\ncheck('middle tie allowed',solve([[p,'a',3],[p,'b',2],[p,'c',2],[p,'d',0]]),[[p,'a','d']])\ncheck('unique extremes',solve([[p,'a',N],[p,'b',0]]),[[p,'a','b']])\ncheck('singleton',solve([[p,'a',N]]),[])\ncheck('empty',solve([]),[])\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":"These are explicit toy record contracts; they do not claim compatibility with a trainer or improved model behavior. 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-preference-pair-construction-tie-skip-group-extrema","generated_at":"2026-09-30T16:48:31.716800+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small deterministic preference-data transform makes pair semantics inspectable without a training framework.","root_cause":"Selecting the first maximum and minimum fabricates a strict preference despite tied ratings.","sha256":"f5ebfcb6d09168582f4137c09c49d94a9f840dcdadfa0baea3ec1616dbbcf595","title":"Preference pairs: tied extrema are resolved by input order · 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":28.548,"exit_code":1,"observations":[{"actual":[],"check":"tied maximum skipped","expected":[],"passed":true},{"actual":[],"check":"tied minimum skipped","expected":[],"passed":true},{"actual":[],"check":"middle tie allowed","expected":[["p1","a","d"]],"passed":false},{"actual":[["p1","a","b"]],"check":"unique extremes","expected":[["p1","a","b"]],"passed":true},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tied maximum skipped\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"tied minimum skipped\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"middle tie allowed\", \"actual\": [], \"expected\": [[\"p1\", \"a\", \"d\"]], \"passed\": false}, {\"check\": \"unique extremes\", \"actual\": [[\"p1\", \"a\", \"b\"]], \"expected\": [[\"p1\", \"a\", \"b\"]], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.705,"exit_code":1,"observations":[{"actual":[["p1","a","c"]],"check":"tied maximum skipped","expected":[],"passed":false},{"actual":[["p1","a","b"]],"check":"tied minimum skipped","expected":[],"passed":false},{"actual":[["p1","a","d"]],"check":"middle tie allowed","expected":[["p1","a","d"]],"passed":true},{"actual":[["p1","a","b"]],"check":"unique extremes","expected":[["p1","a","b"]],"passed":true},{"actual":[],"check":"singleton","expected":[],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"tied maximum skipped\", \"actual\": [[\"p1\", \"a\", \"c\"]], \"expected\": [], \"passed\": false}, {\"check\": \"tied minimum skipped\", \"actual\": [[\"p1\", \"a\", \"b\"]], \"expected\": [], \"passed\": false}, {\"check\": \"middle tie allowed\", \"actual\": [[\"p1\", \"a\", \"d\"]], \"expected\": [[\"p1\", \"a\", \"d\"]], \"passed\": true}, {\"check\": \"unique extremes\", \"actual\": [[\"p1\", \"a\", \"b\"]], \"expected\": [[\"p1\", \"a\", \"b\"]], \"passed\": true}, {\"check\": \"singleton\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"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."}}