{"abstract":"Non-owner replicas contribute gradients for an owned shard.","category":"Distributed training aggregation","checks":6,"contract":"Rows [shard_id, worker_id, owner_id, gradient]; sum only rows where worker equals owner, grouped by shard. Return sorted [shard,total] pairs.","contract_signature":"rows","evaluation_group":"w3-dta-owner-filter","failed_approach":"Selecting one arbitrary replica avoids duplicates but may select a stale non-owner.","family":"w3-distributed-training-aggregation-owner-filter","id":"FA-99276","implementations":{"attempt":{"sha256":"8ad8e9064f0cc6d1419110dff7632d5e6bcfdfb828f3479ba7774d2214b58783","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    d={}\n    for s,w,o,g in rows:\n        if s not in d: d[s]=g\n    return [[s,d[s]] for s in sorted(d)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows0=[['x','a','a',N],['x','b','a',9*N],['y','c','c',2*N]]\ncheck('ignore replica copy',solve(rows0),[['x',N],['y',2*N]])\ncheck('empty owners',solve([]),[])\ncheck('only nonowner',solve([['z','b','a',N]]),[])\ncheck('owner can be late',solve([['z','b','a',N],['z','a','a',3*N]]),[['z',3*N]])\ncheck('several owners',solve([['b','b','b',N],['a','a','a',2*N]]),[['a',2*N],['b',N]])\ncheck('owner contributions add',solve([['q','q','q',N],['q','q','q',2*N]]),[['q',3*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":"d98f27d8469992d930b705c691ccf7776affdba9ba0164844aa593a029014547","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    d={}\n    for s,w,o,g in rows: d[s]=d.get(s,0)+g\n    return [[s,d[s]] for s in sorted(d)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nrows0=[['x','a','a',N],['x','b','a',9*N],['y','c','c',2*N]]\ncheck('ignore replica copy',solve(rows0),[['x',N],['y',2*N]])\ncheck('empty owners',solve([]),[])\ncheck('only nonowner',solve([['z','b','a',N]]),[])\ncheck('owner can be late',solve([['z','b','a',N],['z','a','a',3*N]]),[['z',3*N]])\ncheck('several owners',solve([['b','b','b',N],['a','a','a',2*N]]),[['a',2*N],['b',N]])\ncheck('owner contributions add',solve([['q','q','q',N],['q','q','q',2*N]]),[['q',3*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":"Inputs are already materialized Python values from a fixed toy collective; no transport, failure recovery, optimizer state, or real model behavior is represented. 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-distributed-training-aggregation-owner-filter","generated_at":"2026-09-30T16:48:22.178741+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A toy distributed-training contract makes replica and shard contribution rules explicit without claiming framework compatibility or performance.","root_cause":"Replicated workers may all hold a shard, but only its designated owner contributes its gradient.","sha256":"320a577bb838243d2401079c7e8f708fd5c176cfe25ab261395a0f31a206572e","title":"Non-owner replicas contribute gradients for an owned shard · 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":30.263,"exit_code":1,"observations":[{"actual":[["x",1],["y",2]],"check":"ignore replica copy","expected":[["x",1],["y",2]],"passed":true},{"actual":[],"check":"empty owners","expected":[],"passed":true},{"actual":[["z",1]],"check":"only nonowner","expected":[],"passed":false},{"actual":[["z",1]],"check":"owner can be late","expected":[["z",3]],"passed":false},{"actual":[["a",2],["b",1]],"check":"several owners","expected":[["a",2],["b",1]],"passed":true},{"actual":[["q",1]],"check":"owner contributions add","expected":[["q",3]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignore replica copy\", \"actual\": [[\"x\", 1], [\"y\", 2]], \"expected\": [[\"x\", 1], [\"y\", 2]], \"passed\": true}, {\"check\": \"empty owners\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"only nonowner\", \"actual\": [[\"z\", 1]], \"expected\": [], \"passed\": false}, {\"check\": \"owner can be late\", \"actual\": [[\"z\", 1]], \"expected\": [[\"z\", 3]], \"passed\": false}, {\"check\": \"several owners\", \"actual\": [[\"a\", 2], [\"b\", 1]], \"expected\": [[\"a\", 2], [\"b\", 1]], \"passed\": true}, {\"check\": \"owner contributions add\", \"actual\": [[\"q\", 1]], \"expected\": [[\"q\", 3]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.358,"exit_code":1,"observations":[{"actual":[["x",10],["y",2]],"check":"ignore replica copy","expected":[["x",1],["y",2]],"passed":false},{"actual":[],"check":"empty owners","expected":[],"passed":true},{"actual":[["z",1]],"check":"only nonowner","expected":[],"passed":false},{"actual":[["z",4]],"check":"owner can be late","expected":[["z",3]],"passed":false},{"actual":[["a",2],["b",1]],"check":"several owners","expected":[["a",2],["b",1]],"passed":true},{"actual":[["q",3]],"check":"owner contributions add","expected":[["q",3]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignore replica copy\", \"actual\": [[\"x\", 10], [\"y\", 2]], \"expected\": [[\"x\", 1], [\"y\", 2]], \"passed\": false}, {\"check\": \"empty owners\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"only nonowner\", \"actual\": [[\"z\", 1]], \"expected\": [], \"passed\": false}, {\"check\": \"owner can be late\", \"actual\": [[\"z\", 4]], \"expected\": [[\"z\", 3]], \"passed\": false}, {\"check\": \"several owners\", \"actual\": [[\"a\", 2], [\"b\", 1]], \"expected\": [[\"a\", 2], [\"b\", 1]], \"passed\": true}, {\"check\": \"owner contributions add\", \"actual\": [[\"q\", 3]], \"expected\": [[\"q\", 3]], \"passed\": true}], \"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."}}