{"abstract":"Symmetric quantization retains nonzero zero point.","category":"Model quantization arithmetic","checks":6,"contract":"Symmetric quantization uses signed range [-qmax,qmax], fixed zero point 0, and round-to-even after scale division. Inputs follow this explicit integer toy contract; ties use Python round-to-even where rounding is required.","contract_signature":"values, scale, zero, qmax","evaluation_group":"quant-symmetric_quant","failed_approach":"The attempted code removes the nonzero zero point but truncates scaled values, so fractional codes remain wrong.","family":"w3-model-quantization-arithmetic-symmetric-zero","id":"FA-98726","implementations":{"attempt":{"sha256":"b26e2168034dfce85d88dad81d175247955a4934d7fa9681ec6d6faa7af5e4f3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(values, scale, zero, qmax):\n    return [max(-qmax,min(qmax,int(x/scale))) for x in values]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('positive',solve([2*N],2,7,8),[N])\ncheck('negative',solve([-2*N],2,7,8),[-N])\ncheck('empty',solve([],1,4,8),[])\ncheck('saturate high',solve([100],1,0,8),[8])\ncheck('saturate low',solve([-100],1,0,8),[-8])\ncheck('scale fraction',solve([3],2,0,8),[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":"a63032ac32396643827b47104eb76d75e046060c1bd2cba9f105c6c6781c5e28","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(values, scale, zero, qmax):\n    return [max(-qmax,min(qmax,round(x/scale)+zero)) for x in values]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('positive',solve([2*N],2,7,8),[N])\ncheck('negative',solve([-2*N],2,7,8),[-N])\ncheck('empty',solve([],1,4,8),[])\ncheck('saturate high',solve([100],1,0,8),[8])\ncheck('saturate low',solve([-100],1,0,8),[-8])\ncheck('scale fraction',solve([3],2,0,8),[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":"Toy scalar/list arithmetic only; it does not model a production quantizer, hardware instruction, or accuracy/performance gain. 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-model-quantization-arithmetic-symmetric-zero","generated_at":"2026-09-30T16:48:16.278129+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"This deterministic model isolates one quantization arithmetic contract from tensor storage and runtime kernels.","root_cause":"Symmetric quantization uses signed range [-qmax,qmax], fixed zero point 0, and round-to-even after scale division.","sha256":"89d0417c78a1b5fb394bbf12491fc70462ee03374aab0aca654c2558728a4cf9","title":"Quantization: Symmetric quantization retains nonzero zero point · 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":25.268,"exit_code":1,"observations":[{"actual":[1],"check":"positive","expected":[1],"passed":true},{"actual":[-1],"check":"negative","expected":[-1],"passed":true},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[8],"check":"saturate high","expected":[8],"passed":true},{"actual":[-8],"check":"saturate low","expected":[-8],"passed":true},{"actual":[1],"check":"scale fraction","expected":[2],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"positive\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"negative\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"saturate high\", \"actual\": [8], \"expected\": [8], \"passed\": true}, {\"check\": \"saturate low\", \"actual\": [-8], \"expected\": [-8], \"passed\": true}, {\"check\": \"scale fraction\", \"actual\": [1], \"expected\": [2], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.465,"exit_code":1,"observations":[{"actual":[8],"check":"positive","expected":[1],"passed":false},{"actual":[6],"check":"negative","expected":[-1],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true},{"actual":[8],"check":"saturate high","expected":[8],"passed":true},{"actual":[-8],"check":"saturate low","expected":[-8],"passed":true},{"actual":[2],"check":"scale fraction","expected":[2],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"positive\", \"actual\": [8], \"expected\": [1], \"passed\": false}, {\"check\": \"negative\", \"actual\": [6], \"expected\": [-1], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"saturate high\", \"actual\": [8], \"expected\": [8], \"passed\": true}, {\"check\": \"saturate low\", \"actual\": [-8], \"expected\": [-8], \"passed\": true}, {\"check\": \"scale fraction\", \"actual\": [2], \"expected\": [2], \"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."}}