{"abstract":"A coordinator declares a decision after counting retries or ballots from outside the membership.","category":"Distributed coordination","checks":8,"contract":"Members define a fixed nonempty voting configuration. Return whether distinct eligible voter IDs number at least floor(member count/2)+1; an empty configuration cannot reach quorum.","evaluation_group":"model-cfae8736e001c4dc","failed_approach":"Deduplicating ballot IDs still counts votes from removed or unknown members.","family":"dist-quorum-eligible-votes","id":"FA-066","implementations":{"attempt":{"sha256":"f993907cd45a9eb7d066fa2c64250a3a87a21e2a7fd75f3cb3d1426a21fa6251","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(members, votes):\n    return bool(members) and len(set(votes)) > len(set(members))//2\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nmembers = list(range(2*N+1))\ncheck('retransmitted single ballot', solve(members, [0]*(N+1)), False)\ncheck('only foreign voters', solve(members, list(range(100, 101+N))), False)\ncheck('exact eligible majority', solve(members, list(range(N+1))), True)\ncheck('one below majority', solve(members, list(range(N))), False)\ncheck('noise cannot complete minority', solve(members, list(range(N))+[999]), False)\ncheck('repeats do not destroy real majority', solve(members, list(range(N+1))*N), True)\ncheck('empty configuration', solve([], [0]), False)\ncheck('single eligible member', solve(['only'], ['only']), True)\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":"e86c1b3374ff6c76424d3a6136bfafa6280fe59c7970e97fd5495079b4b3a744","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(members, votes):\n    return bool(members) and len(votes) > len(set(members))//2\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nmembers = list(range(2*N+1))\ncheck('retransmitted single ballot', solve(members, [0]*(N+1)), False)\ncheck('only foreign voters', solve(members, list(range(100, 101+N))), False)\ncheck('exact eligible majority', solve(members, list(range(N+1))), True)\ncheck('one below majority', solve(members, list(range(N))), False)\ncheck('noise cannot complete minority', solve(members, list(range(N))+[999]), False)\ncheck('repeats do not destroy real majority', solve(members, list(range(N+1))*N), True)\ncheck('empty configuration', solve([], [0]), False)\ncheck('single eligible member', solve(['only'], ['only']), True)\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":"a92bc43dfc2ff5b9258ae219a7c2b05700759f4877f181f155e3ca55693db6ea","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(members, votes):\n    eligible = set(members)\n    return bool(eligible) and len(eligible & set(votes)) > len(eligible)//2\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nmembers = list(range(2*N+1))\ncheck('retransmitted single ballot', solve(members, [0]*(N+1)), False)\ncheck('only foreign voters', solve(members, list(range(100, 101+N))), False)\ncheck('exact eligible majority', solve(members, list(range(N+1))), True)\ncheck('one below majority', solve(members, list(range(N))), False)\ncheck('noise cannot complete minority', solve(members, list(range(N))+[999]), False)\ncheck('repeats do not destroy real majority', solve(members, list(range(N+1))*N), True)\ncheck('empty configuration', solve([], [0]), False)\ncheck('single eligible member', solve(['only'], ['only']), True)\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":"dist-quorum-eligible-votes","generated_at":"2026-09-29T14:36:49.896520+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Models quorum accounting independently of transport delivery multiplicity. It deliberately omits cryptographic authentication and joint-consensus membership changes.","repair":"Intersect unique voter IDs with the current membership before testing a strict majority.","root_cause":"The quorum predicate counts received messages instead of distinct eligible voters.","sha256":"a259764003798ac762f6eeb69c38adbdf4be596b3dd6c4f52a01aa988715c27f","title":"Duplicate or foreign ballots manufacture a quorum · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":32.914,"exit_code":1,"observations":[{"actual":false,"check":"retransmitted single ballot","expected":false,"passed":true},{"actual":true,"check":"only foreign voters","expected":false,"passed":false},{"actual":true,"check":"exact eligible majority","expected":true,"passed":true},{"actual":false,"check":"one below majority","expected":false,"passed":true},{"actual":true,"check":"noise cannot complete minority","expected":false,"passed":false},{"actual":true,"check":"repeats do not destroy real majority","expected":true,"passed":true},{"actual":false,"check":"empty configuration","expected":false,"passed":true},{"actual":true,"check":"single eligible member","expected":true,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"retransmitted single ballot\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"only foreign voters\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"exact eligible majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"one below majority\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"noise cannot complete minority\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"repeats do not destroy real majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty configuration\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"single eligible member\", \"actual\": true, \"expected\": true, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.549,"exit_code":1,"observations":[{"actual":true,"check":"retransmitted single ballot","expected":false,"passed":false},{"actual":true,"check":"only foreign voters","expected":false,"passed":false},{"actual":true,"check":"exact eligible majority","expected":true,"passed":true},{"actual":false,"check":"one below majority","expected":false,"passed":true},{"actual":true,"check":"noise cannot complete minority","expected":false,"passed":false},{"actual":true,"check":"repeats do not destroy real majority","expected":true,"passed":true},{"actual":false,"check":"empty configuration","expected":false,"passed":true},{"actual":true,"check":"single eligible member","expected":true,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"retransmitted single ballot\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"only foreign voters\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"exact eligible majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"one below majority\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"noise cannot complete minority\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"repeats do not destroy real majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty configuration\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"single eligible member\", \"actual\": true, \"expected\": true, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":32.118,"exit_code":0,"observations":[{"actual":false,"check":"retransmitted single ballot","expected":false,"passed":true},{"actual":false,"check":"only foreign voters","expected":false,"passed":true},{"actual":true,"check":"exact eligible majority","expected":true,"passed":true},{"actual":false,"check":"one below majority","expected":false,"passed":true},{"actual":false,"check":"noise cannot complete minority","expected":false,"passed":true},{"actual":true,"check":"repeats do not destroy real majority","expected":true,"passed":true},{"actual":false,"check":"empty configuration","expected":false,"passed":true},{"actual":true,"check":"single eligible member","expected":true,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"retransmitted single ballot\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"only foreign voters\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"exact eligible majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"one below majority\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"noise cannot complete minority\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"repeats do not destroy real majority\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"empty configuration\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"single eligible member\", \"actual\": true, \"expected\": true, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}