{"abstract":"two dimensional shard indices use the tile width as row stride.","category":"Checkpoint tensor mapping","checks":6,"contract":"For a 2D global shape and tile shape, coord is a tile-grid [row,column] coordinate. Return the row-major flat positions occupied by the tile, or [] if dimensions are negative or the whole tile lies outside the global shape.","contract_signature":"global_shape, tile_shape, coord","evaluation_group":"w3-checkpoint-tensor-mapping-tile-placement","failed_approach":"Adding the global row stride fixes row placement but omits the column tile offset.","family":"w3-checkpoint-tensor-mapping-tile-placement","id":"FA-99196","implementations":{"attempt":{"sha256":"c0f6296b3f9e906d52598b1b5d8b120f598b7562f7946767bab6bb8c79687ec3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(global_shape, tile_shape, coord):\n    H,W=global_shape\n    th,tw=tile_shape\n    tr,tc=coord\n    return [(tr*th+r)*W+c for r in range(th) for c in range(tw)] if min(H,W,th,tw,tr,tc)>=0 and (tr+1)*th<=H and (tc+1)*tw<=W else []\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('interior tile', solve(*((4, 6), (2, 2), (1, 1))), [14, 15, 20, 21])\ncheck('top left', solve(*((4, 6), (2, 2), (0, 0))), [0, 1, 6, 7])\ncheck('right edge', solve(*((4, 6), (2, 2), (1, 2))), [16, 17, 22, 23])\ncheck('single cell', solve(*((3, 5), (1, 1), (2, 4))), [14])\ncheck('out of rows', solve(*((3, 5), (2, 2), (1, 0))), [])\ncheck('out of columns', solve(*((3, 5), (2, 2), (0, 2))), [])\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":"33cba71d4503f70e8a7a2a7822db42079082103d73f3b55b0182a22b3f5e2bb0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(global_shape, tile_shape, coord):\n    H,W=global_shape\n    th,tw=tile_shape\n    tr,tc=coord\n    return [(tr*th+r)*tw+tc*tw+c for r in range(th) for c in range(tw)] if min(H,W,th,tw,tr,tc)>=0 and (tr+1)*th<=H and (tc+1)*tw<=W else []\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('interior tile', solve(*((4, 6), (2, 2), (1, 1))), [14, 15, 20, 21])\ncheck('top left', solve(*((4, 6), (2, 2), (0, 0))), [0, 1, 6, 7])\ncheck('right edge', solve(*((4, 6), (2, 2), (1, 2))), [16, 17, 22, 23])\ncheck('single cell', solve(*((3, 5), (1, 1), (2, 4))), [14])\ncheck('out of rows', solve(*((3, 5), (2, 2), (1, 0))), [])\ncheck('out of columns', solve(*((3, 5), (2, 2), (0, 2))), [])\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 decoded Python values; this toy contract makes no claim about a framework, file format, or production checkpoint. 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-checkpoint-tensor-mapping-tile-placement","generated_at":"2026-09-30T16:48:21.243208+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A bounded offline model of checkpoint tensor bookkeeping in a training workflow.","root_cause":"Flat positions advance by global row width; using tile width aliases cells from different rows.","sha256":"9e1d0224cebffd0d1efdc2700ae4a9b99e4cfa67787a6a617f067e874fc8c3f9","title":"Checkpoint mapping: two dimensional shard indices use the tile width as row stride · case 01","variant":1,"variant_policy":"The same explicitly authored fixtures repeat across all five numbered records; runtime N is unused. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":27.638,"exit_code":1,"observations":[{"actual":[12,13,18,19],"check":"interior tile","expected":[14,15,20,21],"passed":false},{"actual":[0,1,6,7],"check":"top left","expected":[0,1,6,7],"passed":true},{"actual":[12,13,18,19],"check":"right edge","expected":[16,17,22,23],"passed":false},{"actual":[10],"check":"single cell","expected":[14],"passed":false},{"actual":[],"check":"out of rows","expected":[],"passed":true},{"actual":[],"check":"out of columns","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"interior tile\", \"actual\": [12, 13, 18, 19], \"expected\": [14, 15, 20, 21], \"passed\": false}, {\"check\": \"top left\", \"actual\": [0, 1, 6, 7], \"expected\": [0, 1, 6, 7], \"passed\": true}, {\"check\": \"right edge\", \"actual\": [12, 13, 18, 19], \"expected\": [16, 17, 22, 23], \"passed\": false}, {\"check\": \"single cell\", \"actual\": [10], \"expected\": [14], \"passed\": false}, {\"check\": \"out of rows\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"out of columns\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.882,"exit_code":1,"observations":[{"actual":[6,7,8,9],"check":"interior tile","expected":[14,15,20,21],"passed":false},{"actual":[0,1,2,3],"check":"top left","expected":[0,1,6,7],"passed":false},{"actual":[8,9,10,11],"check":"right edge","expected":[16,17,22,23],"passed":false},{"actual":[6],"check":"single cell","expected":[14],"passed":false},{"actual":[],"check":"out of rows","expected":[],"passed":true},{"actual":[],"check":"out of columns","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"interior tile\", \"actual\": [6, 7, 8, 9], \"expected\": [14, 15, 20, 21], \"passed\": false}, {\"check\": \"top left\", \"actual\": [0, 1, 2, 3], \"expected\": [0, 1, 6, 7], \"passed\": false}, {\"check\": \"right edge\", \"actual\": [8, 9, 10, 11], \"expected\": [16, 17, 22, 23], \"passed\": false}, {\"check\": \"single cell\", \"actual\": [6], \"expected\": [14], \"passed\": false}, {\"check\": \"out of rows\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"out of columns\", \"actual\": [], \"expected\": [], \"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."}}