{"abstract":"child score drops its parent history.","category":"Beam search bookkeeping","checks":6,"contract":"Given parent scores and [parent_index, token_delta] expansions, return cumulative child scores in expansion order.","contract_signature":"parents, expansions","evaluation_group":"beam-cumulative_score","failed_approach":"Taking the larger of parent and child still loses negative log-probability contributions.","family":"w3-beam-search-bookkeeping-cumulative-child-score","id":"FA-98441","implementations":{"attempt":{"sha256":"46d8c8475bd0dfe7b3156b12e745cd01229ea4956d537c889b8eb8bd39ced694","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(parents, expansions):\n    return [max(parents[parent],delta) for parent,delta in expansions]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('two parent histories',solve([-N,-2*N],[[0,-1],[1,-2]]),[-N-1,-2*N-2])\ncheck('negative child contribution',solve([0],[[0,-N]]),[-N])\ncheck('positive toy contribution',solve([N],[[0,2]]),[N+2])\ncheck('no expansions',solve([N],[]),[])\ncheck('repeated parent',solve([-N],[[0,-1],[0,-3]]),[-N-1,-N-3])\ncheck('later parent selected',solve([0,-N],[[1,1]]),[1-N])\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":"290237311442e3ba25ea23b1269b1c5c9e5c858f579368dbd43d903605eb598d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(parents, expansions):\n    return [delta for parent,delta in expansions]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('two parent histories',solve([-N,-2*N],[[0,-1],[1,-2]]),[-N-1,-2*N-2])\ncheck('negative child contribution',solve([0],[[0,-N]]),[-N])\ncheck('positive toy contribution',solve([N],[[0,2]]),[N+2])\ncheck('no expansions',solve([N],[]),[])\ncheck('repeated parent',solve([-N],[[0,-1],[0,-3]]),[-N-1,-N-3])\ncheck('later parent selected',solve([0,-N],[[1,1]]),[1-N])\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 is a finite toy beam-state contract and makes no claim about neural model quality or production decoding. 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-beam-search-bookkeeping-cumulative-child-score","generated_at":"2026-09-30T16:48:13.239133+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Beam decoders rely on consistent hypothesis state while expanding and ranking candidates.","root_cause":"Expansion replaces a hypothesis score with only the newest token contribution.","sha256":"03471caaa696f30ffa7e6a85e7b6c158b3e6b1af5a860c7c9967ea2aabb91d08","title":"Beam search: child score drops its parent history · 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":27.751,"exit_code":1,"observations":[{"actual":[-1,-2],"check":"two parent histories","expected":[-2,-4],"passed":false},{"actual":[0],"check":"negative child contribution","expected":[-1],"passed":false},{"actual":[2],"check":"positive toy contribution","expected":[3],"passed":false},{"actual":[],"check":"no expansions","expected":[],"passed":true},{"actual":[-1,-1],"check":"repeated parent","expected":[-2,-4],"passed":false},{"actual":[1],"check":"later parent selected","expected":[0],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"two parent histories\", \"actual\": [-1, -2], \"expected\": [-2, -4], \"passed\": false}, {\"check\": \"negative child contribution\", \"actual\": [0], \"expected\": [-1], \"passed\": false}, {\"check\": \"positive toy contribution\", \"actual\": [2], \"expected\": [3], \"passed\": false}, {\"check\": \"no expansions\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"repeated parent\", \"actual\": [-1, -1], \"expected\": [-2, -4], \"passed\": false}, {\"check\": \"later parent selected\", \"actual\": [1], \"expected\": [0], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":26.892,"exit_code":1,"observations":[{"actual":[-1,-2],"check":"two parent histories","expected":[-2,-4],"passed":false},{"actual":[-1],"check":"negative child contribution","expected":[-1],"passed":true},{"actual":[2],"check":"positive toy contribution","expected":[3],"passed":false},{"actual":[],"check":"no expansions","expected":[],"passed":true},{"actual":[-1,-3],"check":"repeated parent","expected":[-2,-4],"passed":false},{"actual":[1],"check":"later parent selected","expected":[0],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"two parent histories\", \"actual\": [-1, -2], \"expected\": [-2, -4], \"passed\": false}, {\"check\": \"negative child contribution\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"positive toy contribution\", \"actual\": [2], \"expected\": [3], \"passed\": false}, {\"check\": \"no expansions\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"repeated parent\", \"actual\": [-1, -3], \"expected\": [-2, -4], \"passed\": false}, {\"check\": \"later parent selected\", \"actual\": [1], \"expected\": [0], \"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."}}