{"abstract":"Branch and bound prunes against an infeasible incumbent.","category":"Optimization solver contracts","checks":6,"contract":"Minimization, one optimum required: prune iff incumbent is feasible and node lower bound>=incumbent objective.","contract_signature":"lower, incumbent, feasible","evaluation_group":"model-d7e43b2e78a7390a","failed_approach":"Checking feasibility but using strict inequality needlessly explores equal bounds under single-optimum semantics.","family":"z-optimization-bound-pruning","id":"FA-12006","implementations":{"attempt":{"sha256":"8b6bd09ec4884f6e5316d4693d81310b764caecfa545038c2f8cfa02f2fd7714","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(lower, incumbent, feasible):\n    return feasible and lower > incumbent\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('infeasible estimate', solve(10*N, N, False), False)\ncheck('equal bound', solve(N, N, True), True)\ncheck('strictly dominated', solve(N+1, N, True), True)\ncheck('possible improvement', solve(N-1, N, True), False)\ncheck('negative objectives', solve(-N, -N-1, True), True)\ncheck('infeasible equal', solve(N, N, False), 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":"c575cd37eaa374a43e7e3e247ed3ac87f164dd972862b868297f20da24977bd1","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(lower, incumbent, feasible):\n    return lower >= incumbent\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('infeasible estimate', solve(10*N, N, False), False)\ncheck('equal bound', solve(N, N, True), True)\ncheck('strictly dominated', solve(N+1, N, True), True)\ncheck('possible improvement', solve(N-1, N, True), False)\ncheck('negative objectives', solve(-N, -N-1, True), True)\ncheck('infeasible equal', solve(N, N, False), 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-bound-pruning","generated_at":"2026-09-29T14:38:52.992535+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.","root_cause":"An objective estimate is treated as a feasible incumbent.","sha256":"bb24d7f4300c2c04caf2c3ccf6a860ec470086335413c5b6ef1c506f4cd6b200","title":"Branch and bound prunes against an infeasible incumbent · 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":40.564,"exit_code":1,"observations":[{"actual":false,"check":"infeasible estimate","expected":false,"passed":true},{"actual":false,"check":"equal bound","expected":true,"passed":false},{"actual":true,"check":"strictly dominated","expected":true,"passed":true},{"actual":false,"check":"possible improvement","expected":false,"passed":true},{"actual":true,"check":"negative objectives","expected":true,"passed":true},{"actual":false,"check":"infeasible equal","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"infeasible estimate\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"equal bound\", \"actual\": false, \"expected\": true, \"passed\": false}, {\"check\": \"strictly dominated\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"possible improvement\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"negative objectives\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"infeasible equal\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.859,"exit_code":1,"observations":[{"actual":true,"check":"infeasible estimate","expected":false,"passed":false},{"actual":true,"check":"equal bound","expected":true,"passed":true},{"actual":true,"check":"strictly dominated","expected":true,"passed":true},{"actual":false,"check":"possible improvement","expected":false,"passed":true},{"actual":true,"check":"negative objectives","expected":true,"passed":true},{"actual":true,"check":"infeasible equal","expected":false,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"infeasible estimate\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"equal bound\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"strictly dominated\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"possible improvement\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"negative objectives\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"infeasible equal\", \"actual\": true, \"expected\": false, \"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."}}