{"abstract":"The operation returns a result or retained state that violates this contract: Return whether right is an order-preserving, multiplicity-respecting subsequence of left.","category":"Collection algebra","checks":6,"contract":"Return whether right is an order-preserving, multiplicity-respecting subsequence of left. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","evaluation_group":"model-53ee5f6d70b61c11","failed_approach":"Contiguous-window search rejects valid gapped subsequences.","family":"xr-subsequence-not-subset","id":"FA-4286","implementations":{"attempt":{"sha256":"f020cb2a87059e3bdf6c1829f2e787deb7297aad1d5feef39ba62626dfdf2a7d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return any(x[i:i+len(y)]==y for i in range(len(x)+1))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('both empty', solve([], []), True)\ncheck('empty right operand', solve(['a'], []), True)\ncheck('empty left operand', solve([], ['b']), False)\ncheck('overlap and multiplicity', solve(['b', 'a', 'b'], ['b', 'c', 'c']), False)\ncheck('gapped subsequence succeeds', solve(['a','b','c'], ['a','c']), True)\ncheck('reusing occurrence is forbidden', solve(['a'], ['a','a']), 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":"048819b09a83277988b25072648e9ee9d8b826b97a8d3e02256d90f080a6b6db","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return all(v in x for v in y)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('both empty', solve([], []), True)\ncheck('empty right operand', solve(['a'], []), True)\ncheck('empty left operand', solve([], ['b']), False)\ncheck('overlap and multiplicity', solve(['b', 'a', 'b'], ['b', 'c', 'c']), False)\ncheck('gapped subsequence succeeds', solve(['a','b','c'], ['a','c']), True)\ncheck('reusing occurrence is forbidden', solve(['a'], ['a','a']), 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"},"fixed":{"sha256":"e60defdbec8dd5d60086d157986efb4bce3679d509fa90da4bc82a6d14ff3f7a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return (lambda it: all(any(v==a for a in it) for v in y))(iter(x))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('both empty', solve([], []), True)\ncheck('empty right operand', solve(['a'], []), True)\ncheck('empty left operand', solve([], ['b']), False)\ncheck('overlap and multiplicity', solve(['b', 'a', 'b'], ['b', 'c', 'c']), False)\ncheck('gapped subsequence succeeds', solve(['a','b','c'], ['a','c']), True)\ncheck('reusing occurrence is forbidden', solve(['a'], ['a','a']), 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":" 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":"xr-subsequence-not-subset","generated_at":"2026-09-29T14:37:37.566268+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.","repair":"Return whether right is an order-preserving, multiplicity-respecting subsequence of left.","root_cause":"Independent membership tests reuse positions and ignore order.","sha256":"8912b6bdf5622743059ebf0cfefbee4dcd13ef092192f5ed0e3729610549d50a","title":"Subsequence not subset · case 01","variant":1,"variant_policy":"Five execution reruns of a fixed adversarial fixture suite; variant number does not alter semantic inputs.","verification":{"attempt":{"elapsed_ms":41.702,"exit_code":1,"observations":[{"actual":true,"check":"both empty","expected":true,"passed":true},{"actual":true,"check":"empty right operand","expected":true,"passed":true},{"actual":false,"check":"empty left operand","expected":false,"passed":true},{"actual":false,"check":"overlap and multiplicity","expected":false,"passed":true},{"actual":false,"check":"gapped subsequence succeeds","expected":true,"passed":false},{"actual":false,"check":"reusing occurrence is forbidden","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"both empty\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty right operand\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty left operand\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"overlap and multiplicity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"gapped subsequence succeeds\", \"actual\": false, \"expected\": true, \"passed\": false}, {\"check\": \"reusing occurrence is forbidden\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.755,"exit_code":1,"observations":[{"actual":true,"check":"both empty","expected":true,"passed":true},{"actual":true,"check":"empty right operand","expected":true,"passed":true},{"actual":false,"check":"empty left operand","expected":false,"passed":true},{"actual":false,"check":"overlap and multiplicity","expected":false,"passed":true},{"actual":true,"check":"gapped subsequence succeeds","expected":true,"passed":true},{"actual":true,"check":"reusing occurrence is forbidden","expected":false,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"both empty\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty right operand\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty left operand\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"overlap and multiplicity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"gapped subsequence succeeds\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"reusing occurrence is forbidden\", \"actual\": true, \"expected\": false, \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.092,"exit_code":0,"observations":[{"actual":true,"check":"both empty","expected":true,"passed":true},{"actual":true,"check":"empty right operand","expected":true,"passed":true},{"actual":false,"check":"empty left operand","expected":false,"passed":true},{"actual":false,"check":"overlap and multiplicity","expected":false,"passed":true},{"actual":true,"check":"gapped subsequence succeeds","expected":true,"passed":true},{"actual":false,"check":"reusing occurrence is forbidden","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"both empty\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty right operand\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty left operand\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"overlap and multiplicity\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"gapped subsequence succeeds\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"reusing occurrence is forbidden\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}