{"abstract":"Evaluates the right operand before knowing whether the first comparison passes and changes the required Python-language result.","category":"Python evaluation","checks":5,"contract":"Evaluate lhs() < middle() < rhs(). Evaluate the middle expression once, evaluate each operand left-to-right, and skip the final expression when the first comparison fails. Both inequalities are strict. Inputs use the finite Python types shown in the fixtures. An error string denotes the specified caught exception, not an unhandled process failure.","evaluation_group":"xl-chained-comparison-evaluation","failed_approach":"The alternative still fails because it changes the first strict comparison into an inclusive one.","family":"xl-chained-comparison-evaluation-eager-final-operand","id":"FA-5311","implementations":{"attempt":{"sha256":"bc851304bb1fd113daa46551ac26ccbb85d2770cca61c0c4aa990f6c7664dab5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(left, mid, right):\n    trace=[]\n    def lhs(): trace.append('left'); return left\n    def middle(): trace.append('middle'); return mid\n    def rhs(): trace.append('right'); return right\n    result=lhs() <= middle() < rhs()\n    return [result,trace]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('increasing triple', solve(1, 2, 3), [True, ['left', 'middle', 'right']])\ncheck('first comparison fails', solve(3, 2, 9), [False, ['left', 'middle']])\ncheck('equal first operands', solve(2, 2, 3), [False, ['left', 'middle']])\ncheck('equal last operands', solve(1, 2, 2), [False, ['left', 'middle', 'right']])\ncheck('second comparison fails', solve(1, 3, 2), [False, ['left', 'middle', 'right']])\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":"b49e3b76420f30a7db98ae43fa9d7edb7c354be43d59a1b05f93bdbb502404cd","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(left, mid, right):\n    trace=[]\n    def lhs(): trace.append('left'); return left\n    def middle(): trace.append('middle'); return mid\n    def rhs(): trace.append('right'); return right\n    a,b,c=lhs(),middle(),rhs()\n    return [a<b<c,trace]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('increasing triple', solve(1, 2, 3), [True, ['left', 'middle', 'right']])\ncheck('first comparison fails', solve(3, 2, 9), [False, ['left', 'middle']])\ncheck('equal first operands', solve(2, 2, 3), [False, ['left', 'middle']])\ncheck('equal last operands', solve(1, 2, 2), [False, ['left', 'middle', 'right']])\ncheck('second comparison fails', solve(1, 3, 2), [False, ['left', 'middle', 'right']])\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":"2e00ac85bd278ba821bd7a185101168446ef53f78f007ccb5a4ae6cc027c6315","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(left, mid, right):\n    trace=[]\n    def lhs(): trace.append('left'); return left\n    def middle(): trace.append('middle'); return mid\n    def rhs(): trace.append('right'); return right\n    result=lhs() < middle() < rhs()\n    return [result,trace]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('increasing triple', solve(1, 2, 3), [True, ['left', 'middle', 'right']])\ncheck('first comparison fails', solve(3, 2, 9), [False, ['left', 'middle']])\ncheck('equal first operands', solve(2, 2, 3), [False, ['left', 'middle']])\ncheck('equal last operands', solve(1, 2, 2), [False, ['left', 'middle', 'right']])\ncheck('second comparison fails', solve(1, 3, 2), [False, ['left', 'middle', 'right']])\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":"xl-chained-comparison-evaluation-eager-final-operand","generated_at":"2026-09-29T14:37:48.012838+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Runs Python standard-library language operations in a deterministic local reproducer. Literal expected answers are authored independently. Related defects share an evaluation group to avoid benchmark split leakage.","repair":"Evaluate lhs() < middle() < rhs(). Evaluate the middle expression once, evaluate each operand left-to-right, and skip the final expression when the first comparison fails. Both inequalities are strict.","root_cause":"Evaluates the right operand before knowing whether the first comparison passes. The executable reproducer isolates this operation from the rest of the contract.","sha256":"9ed2a95ee492db509b974ac0640d77ff037a6a4f6cbc65ba74f332207c00d916","title":"Chained comparison evaluation: Evaluates the right operand before knowing whether the first comparison passes · case 01","variant":1,"variant_policy":"The five numbered cases rerun the same authored boundary fixtures; they are reproducibility runs, not independent input variants.","verification":{"attempt":{"elapsed_ms":38.813,"exit_code":1,"observations":[{"actual":[true,["left","middle","right"]],"check":"increasing triple","expected":[true,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle"]],"check":"first comparison fails","expected":[false,["left","middle"]],"passed":true},{"actual":[true,["left","middle","right"]],"check":"equal first operands","expected":[false,["left","middle"]],"passed":false},{"actual":[false,["left","middle","right"]],"check":"equal last operands","expected":[false,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle","right"]],"check":"second comparison fails","expected":[false,["left","middle","right"]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"increasing triple\", \"actual\": [true, [\"left\", \"middle\", \"right\"]], \"expected\": [true, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"first comparison fails\", \"actual\": [false, [\"left\", \"middle\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": true}, {\"check\": \"equal first operands\", \"actual\": [true, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": false}, {\"check\": \"equal last operands\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"second comparison fails\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.414,"exit_code":1,"observations":[{"actual":[true,["left","middle","right"]],"check":"increasing triple","expected":[true,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle","right"]],"check":"first comparison fails","expected":[false,["left","middle"]],"passed":false},{"actual":[false,["left","middle","right"]],"check":"equal first operands","expected":[false,["left","middle"]],"passed":false},{"actual":[false,["left","middle","right"]],"check":"equal last operands","expected":[false,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle","right"]],"check":"second comparison fails","expected":[false,["left","middle","right"]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"increasing triple\", \"actual\": [true, [\"left\", \"middle\", \"right\"]], \"expected\": [true, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"first comparison fails\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": false}, {\"check\": \"equal first operands\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": false}, {\"check\": \"equal last operands\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"second comparison fails\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":36.759,"exit_code":0,"observations":[{"actual":[true,["left","middle","right"]],"check":"increasing triple","expected":[true,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle"]],"check":"first comparison fails","expected":[false,["left","middle"]],"passed":true},{"actual":[false,["left","middle"]],"check":"equal first operands","expected":[false,["left","middle"]],"passed":true},{"actual":[false,["left","middle","right"]],"check":"equal last operands","expected":[false,["left","middle","right"]],"passed":true},{"actual":[false,["left","middle","right"]],"check":"second comparison fails","expected":[false,["left","middle","right"]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"increasing triple\", \"actual\": [true, [\"left\", \"middle\", \"right\"]], \"expected\": [true, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"first comparison fails\", \"actual\": [false, [\"left\", \"middle\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": true}, {\"check\": \"equal first operands\", \"actual\": [false, [\"left\", \"middle\"]], \"expected\": [false, [\"left\", \"middle\"]], \"passed\": true}, {\"check\": \"equal last operands\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}, {\"check\": \"second comparison fails\", \"actual\": [false, [\"left\", \"middle\", \"right\"]], \"expected\": [false, [\"left\", \"middle\", \"right\"]], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}