{"abstract":"Manhattan distance replaces squared Euclidean distance.","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. Squared point distance. Exact operational definition: sum((x-y)**2 for x,y in zip(a,b))","contract_signature":"a, b","evaluation_group":"model-29a6ee7c485562f1","failed_approach":"Squaring the sum introduces cross terms and cancellation.","family":"xn-squared-point-distance","id":"FA-5781","implementations":{"attempt":{"sha256":"b00ce21369ae2f13944eba9811902b4e1d380ac6cf5dec1f099e8d178c823807","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 sum(x-y for x,y in zip(a,b))**2\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1: ((0, 0), (3, 4))', solve(*((0, 0), (3, 4))), 25)\ncheck('fixture 2: ((1, 2), (1, 2))', solve(*((1, 2), (1, 2))), 0)\ncheck('fixture 3: ((0, 0), (1, -1))', solve(*((0, 0), (1, -1))), 2)\ncheck('fixture 4: ((-2, 0), (2, 0))', solve(*((-2, 0), (2, 0))), 16)\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":"fb776eacedca275cd58f636e61f0d930709f0f108c708e18e989e54e96104ac6","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 sum(abs(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('fixture 1: ((0, 0), (3, 4))', solve(*((0, 0), (3, 4))), 25)\ncheck('fixture 2: ((1, 2), (1, 2))', solve(*((1, 2), (1, 2))), 0)\ncheck('fixture 3: ((0, 0), (1, -1))', solve(*((0, 0), (1, -1))), 2)\ncheck('fixture 4: ((-2, 0), (2, 0))', solve(*((-2, 0), (2, 0))), 16)\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-squared-point-distance","generated_at":"2026-09-29T14:37:53.638062+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":"Manhattan distance replaces squared Euclidean distance.","sha256":"ed43bf916f7ced9368e91e57b6b376ba829ca697e3bcd767253adb059713d0f7","title":"Squared point distance · 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":143.561,"exit_code":1,"observations":[{"actual":49,"check":"fixture 1: ((0, 0), (3, 4))","expected":25,"passed":false},{"actual":0,"check":"fixture 2: ((1, 2), (1, 2))","expected":0,"passed":true},{"actual":0,"check":"fixture 3: ((0, 0), (1, -1))","expected":2,"passed":false},{"actual":16,"check":"fixture 4: ((-2, 0), (2, 0))","expected":16,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: ((0, 0), (3, 4))\", \"actual\": 49, \"expected\": 25, \"passed\": false}, {\"check\": \"fixture 2: ((1, 2), (1, 2))\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 3: ((0, 0), (1, -1))\", \"actual\": 0, \"expected\": 2, \"passed\": false}, {\"check\": \"fixture 4: ((-2, 0), (2, 0))\", \"actual\": 16, \"expected\": 16, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":49.536,"exit_code":1,"observations":[{"actual":7,"check":"fixture 1: ((0, 0), (3, 4))","expected":25,"passed":false},{"actual":0,"check":"fixture 2: ((1, 2), (1, 2))","expected":0,"passed":true},{"actual":2,"check":"fixture 3: ((0, 0), (1, -1))","expected":2,"passed":true},{"actual":4,"check":"fixture 4: ((-2, 0), (2, 0))","expected":16,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1: ((0, 0), (3, 4))\", \"actual\": 7, \"expected\": 25, \"passed\": false}, {\"check\": \"fixture 2: ((1, 2), (1, 2))\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 3: ((0, 0), (1, -1))\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"fixture 4: ((-2, 0), (2, 0))\", \"actual\": 4, \"expected\": 16, \"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."}}