{"abstract":"Trust region accepts steps with a nondecreasing model.","category":"Optimization solver contracts","checks":6,"contract":"Accept iff predicted>0 and actual/predicted>=eta, for 0<eta<1; reductions use old-new convention.","evaluation_group":"model-7efd2a3a67757ec2","failed_approach":"Taking absolute predicted reduction masks a model that forecasts an increase.","family":"z-optimization-trust-ratio","id":"FA-12021","implementations":{"attempt":{"sha256":"0f56f86ffec3b72df42aa9cdd618d6479d62e392327e28aa71efe019b97e6c57","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(actual, predicted, eta):\n    return predicted != 0 and actual/abs(predicted) >= eta\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('model increase', solve(N, -N, 0.5), False)\ncheck('poor agreement', solve(N, 10*N, 0.5), False)\ncheck('threshold', solve(N, 2*N, 0.5), True)\ncheck('good agreement', solve(2*N, N, 0.5), True)\ncheck('flat model', solve(N, 0, 0.5), False)\ncheck('actual increase', solve(-N, N, 0.5), False)\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":"d475b94f1cea49cf1dd54899665ebb6b10f7877768b4230fc83f1d4385901aa8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(actual, predicted, eta):\n    return actual > 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('model increase', solve(N, -N, 0.5), False)\ncheck('poor agreement', solve(N, 10*N, 0.5), False)\ncheck('threshold', solve(N, 2*N, 0.5), True)\ncheck('good agreement', solve(2*N, N, 0.5), True)\ncheck('flat model', solve(N, 0, 0.5), False)\ncheck('actual increase', solve(-N, N, 0.5), False)\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"},"fixed":{"sha256":"f35f9f2470fb05db35b9e1253c238c6c9c5ddf30f7f8d4daeebf8b579e1354f0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(actual, predicted, eta):\n    return predicted > 0 and actual/predicted >= eta\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('model increase', solve(N, -N, 0.5), False)\ncheck('poor agreement', solve(N, 10*N, 0.5), False)\ncheck('threshold', solve(N, 2*N, 0.5), True)\ncheck('good agreement', solve(2*N, N, 0.5), True)\ncheck('flat model', solve(N, 0, 0.5), False)\ncheck('actual increase', solve(-N, N, 0.5), False)\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":"Controlled finite inputs and explicit one-step contracts; this is not a production solver or a numerical stability benchmark. 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":"z-optimization-trust-ratio","generated_at":"2026-09-29T14:38:53.038173+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic solver-step model isolates an algorithmic invariant used by iterative optimization implementations.","repair":"Require positive predicted reduction and ratio at least eta.","root_cause":"Acceptance tests actual improvement without predicted reduction.","sha256":"c94a9365a8d12a3ed84a8763d9b1b3d5158b106869157ff353b35e862a2e8ab5","title":"Trust region accepts steps with a nondecreasing model · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":41.506,"exit_code":1,"observations":[{"actual":true,"check":"model increase","expected":false,"passed":false},{"actual":false,"check":"poor agreement","expected":false,"passed":true},{"actual":true,"check":"threshold","expected":true,"passed":true},{"actual":true,"check":"good agreement","expected":true,"passed":true},{"actual":false,"check":"flat model","expected":false,"passed":true},{"actual":false,"check":"actual increase","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"model increase\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"poor agreement\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"threshold\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"good agreement\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"flat model\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"actual increase\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.909,"exit_code":1,"observations":[{"actual":true,"check":"model increase","expected":false,"passed":false},{"actual":true,"check":"poor agreement","expected":false,"passed":false},{"actual":true,"check":"threshold","expected":true,"passed":true},{"actual":true,"check":"good agreement","expected":true,"passed":true},{"actual":true,"check":"flat model","expected":false,"passed":false},{"actual":false,"check":"actual increase","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"model increase\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"poor agreement\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"threshold\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"good agreement\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"flat model\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"actual increase\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.873,"exit_code":0,"observations":[{"actual":false,"check":"model increase","expected":false,"passed":true},{"actual":false,"check":"poor agreement","expected":false,"passed":true},{"actual":true,"check":"threshold","expected":true,"passed":true},{"actual":true,"check":"good agreement","expected":true,"passed":true},{"actual":false,"check":"flat model","expected":false,"passed":true},{"actual":false,"check":"actual increase","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"model increase\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"poor agreement\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"threshold\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"good agreement\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"flat model\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"actual increase\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}