{"abstract":"Only one semiaxis determines the area.","category":"Planar geometry","checks":4,"contract":"Integer coordinates and lengths, with exact arithmetic except for indicated division results. Lengths are nonnegative. Rectangles are (xmin,ymin,xmax,ymax) with ordered bounds; coordinate vectors have matching dimensions. Ellipse area divided by pi. Exact operational definition: a*b","contract_signature":"a, b","evaluation_group":"model-d66a906824ce95d4","failed_approach":"Averaging axes first introduces an incorrect cross-section.","family":"xn-ellipse-area-divided-by-pi","id":"FA-5806","implementations":{"attempt":{"sha256":"db1dc486a6f762827b461f76bf0d1276b707a9e18b5e66b1718cfa5aefd986ce","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(a, b):\n    return (a+b)**2/4\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (3, 2)', solve(*(3, 2)), 6)\ncheck('fixture 2: (2, 2)', solve(*(2, 2)), 4)\ncheck('fixture 3: (0, 5)', solve(*(0, 5)), 0)\ncheck('fixture 4: (4, 1)', solve(*(4, 1)), 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":"7f533ae6437ec47f7bb5befcd9179223db8999bf9fa2b2f24db77a946282373f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nimport calendar\nimport statistics\nimport itertools\nfrom fractions import Fraction\nfrom datetime import date, datetime, timedelta, timezone\nfrom decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR\n\nN = 1\nobservations = []\ndef solve(a, b):\n    return a*a\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: (3, 2)', solve(*(3, 2)), 6)\ncheck('fixture 2: (2, 2)', solve(*(2, 2)), 4)\ncheck('fixture 3: (0, 5)', solve(*(0, 5)), 0)\ncheck('fixture 4: (4, 1)', solve(*(4, 1)), 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":" 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":"xn-ellipse-area-divided-by-pi","generated_at":"2026-09-29T14:37:53.835140+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Planar geometry results depend on the stated convention.","root_cause":"Only one semiaxis determines the area.","sha256":"4c9f2c40f8a40f49822b8cba6b745cde04feb148a6eb51ac8c38c239e240fed0","title":"Ellipse area divided by pi · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":44.34,"exit_code":1,"observations":[{"actual":6.25,"check":"fixture 1: (3, 2)","expected":6,"passed":false},{"actual":4.0,"check":"fixture 2: (2, 2)","expected":4,"passed":true},{"actual":6.25,"check":"fixture 3: (0, 5)","expected":0,"passed":false},{"actual":6.25,"check":"fixture 4: (4, 1)","expected":4,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (3, 2)\", \"actual\": 6.25, \"expected\": 6, \"passed\": false}, {\"check\": \"fixture 2: (2, 2)\", \"actual\": 4.0, \"expected\": 4, \"passed\": true}, {\"check\": \"fixture 3: (0, 5)\", \"actual\": 6.25, \"expected\": 0, \"passed\": false}, {\"check\": \"fixture 4: (4, 1)\", \"actual\": 6.25, \"expected\": 4, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":48.811,"exit_code":1,"observations":[{"actual":9,"check":"fixture 1: (3, 2)","expected":6,"passed":false},{"actual":4,"check":"fixture 2: (2, 2)","expected":4,"passed":true},{"actual":0,"check":"fixture 3: (0, 5)","expected":0,"passed":true},{"actual":16,"check":"fixture 4: (4, 1)","expected":4,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: (3, 2)\", \"actual\": 9, \"expected\": 6, \"passed\": false}, {\"check\": \"fixture 2: (2, 2)\", \"actual\": 4, \"expected\": 4, \"passed\": true}, {\"check\": \"fixture 3: (0, 5)\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 4: (4, 1)\", \"actual\": 16, \"expected\": 4, \"passed\": false}], \"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."}}