{"abstract":"Hyphen-grouped card numbers are rejected as malformed.","category":"Check-digit algorithms","checks":8,"contract":"Input a card-style number that may contain spaces or hyphens as group separators. After removing them the text must be 2..19 ASCII digits, otherwise \"malformed\". Doubling applies to every second digit counting from the rightmost (check) digit, doubled values above 9 lose 9, and the number is \"valid\" when the sum is a multiple of 10, else \"invalid\".","evaluation_group":"w2-check_digit_algorithms-luhn-validate","failed_approach":"Keeping every digit character silently accepts letters and other junk as if they were separators.","family":"w2-check_digit_algorithms-luhn-validate-separator-normalization","id":"FA-72351","implementations":{"attempt":{"sha256":"a1909b0d5e7f482133005eef921710ae3b73619610b715746bf023dd86a79f61","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(s):\n    t = ''.join(c for c in s if c.isdigit())\n    if not t.isascii() or not t.isdigit() or len(t) < 2 or len(t) > 19:\n        return 'malformed'\n    total = 0\n    for i, ch in enumerate(reversed(t)):\n        d = ord(ch) - 48\n        if i % 2 == 1:\n            d *= 2\n            if d > 9:\n                d -= 9\n        total += d\n    return 'valid' if total % 10 == 0 else 'invalid'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"59\"]', ['59'], 'valid'], ['control [\"182\"]', ['182'], 'valid'], ['control [\"97956\"]', ['97956'], 'valid'], ['control [\"60866456\"]', ['60866456'], 'valid'], ['control [\"49717735275\"]', ['49717735275'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"9207919074163\"]', ['9207919074163'], 'valid'], ['control [\"470663048070284\"]', ['470663048070284'], 'valid'], ['control [\"2300017738893848\"]', ['2300017738893848'], 'valid'], ['control [\"7985145013991721\"]', ['7985145013991721'], 'valid'], ['control [\"067122965057139178\"]', ['067122965057139178'], 'valid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"1513156399001929628\"]', ['1513156399001929628'], 'valid'], ['control [\"9505094299844733505\"]', ['9505094299844733505'], 'valid'], ['control [\"0906050370970\"]', ['0906050370970'], 'valid'], ['control [\"3165356977\"]', ['3165356977'], 'valid'], ['control [\"91\"]', ['91'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"992\"]', ['992'], 'valid'], ['control [\"5553\"]', ['5553'], 'valid'], ['control [\"77777779\"]', ['77777779'], 'valid'], ['control [\"52\"]', ['52'], 'invalid'], ['control [\"185\"]', ['185'], 'invalid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"97959\"]', ['97959'], 'invalid'], ['control [\"60866459\"]', ['60866459'], 'invalid'], ['control [\"49717735278\"]', ['49717735278'], 'invalid'], ['control [\"9207919074166\"]', ['9207919074166'], 'invalid'], ['control [\"470663048070287\"]', ['470663048070287'], 'invalid']]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\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":"ce869e502a48ebbf66e770e919b43b1aa3c4ffbba28843d1fae7a6a15bc3f0dc","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(s):\n    t = s.replace(' ', '')\n    if not t.isascii() or not t.isdigit() or len(t) < 2 or len(t) > 19:\n        return 'malformed'\n    total = 0\n    for i, ch in enumerate(reversed(t)):\n        d = ord(ch) - 48\n        if i % 2 == 1:\n            d *= 2\n            if d > 9:\n                d -= 9\n        total += d\n    return 'valid' if total % 10 == 0 else 'invalid'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"59\"]', ['59'], 'valid'], ['control [\"182\"]', ['182'], 'valid'], ['control [\"97956\"]', ['97956'], 'valid'], ['control [\"60866456\"]', ['60866456'], 'valid'], ['control [\"49717735275\"]', ['49717735275'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"9207919074163\"]', ['9207919074163'], 'valid'], ['control [\"470663048070284\"]', ['470663048070284'], 'valid'], ['control [\"2300017738893848\"]', ['2300017738893848'], 'valid'], ['control [\"7985145013991721\"]', ['7985145013991721'], 'valid'], ['control [\"067122965057139178\"]', ['067122965057139178'], 'valid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"1513156399001929628\"]', ['1513156399001929628'], 'valid'], ['control [\"9505094299844733505\"]', ['9505094299844733505'], 'valid'], ['control [\"0906050370970\"]', ['0906050370970'], 'valid'], ['control [\"3165356977\"]', ['3165356977'], 'valid'], ['control [\"91\"]', ['91'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"992\"]', ['992'], 'valid'], ['control [\"5553\"]', ['5553'], 'valid'], ['control [\"77777779\"]', ['77777779'], 'valid'], ['control [\"52\"]', ['52'], 'invalid'], ['control [\"185\"]', ['185'], 'invalid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"97959\"]', ['97959'], 'invalid'], ['control [\"60866459\"]', ['60866459'], 'invalid'], ['control [\"49717735278\"]', ['49717735278'], 'invalid'], ['control [\"9207919074166\"]', ['9207919074166'], 'invalid'], ['control [\"470663048070287\"]', ['470663048070287'], 'invalid']]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\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":"79518d70bb9bbdc3f3c866b0200ab91a77cd25aa3ba6e8bf898b3dc11ed7fb2d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(s):\n    t = s.replace(' ', '').replace('-', '')\n    if not t.isascii() or not t.isdigit() or len(t) < 2 or len(t) > 19:\n        return 'malformed'\n    total = 0\n    for i, ch in enumerate(reversed(t)):\n        d = ord(ch) - 48\n        if i % 2 == 1:\n            d *= 2\n            if d > 9:\n                d -= 9\n        total += d\n    return 'valid' if total % 10 == 0 else 'invalid'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"59\"]', ['59'], 'valid'], ['control [\"182\"]', ['182'], 'valid'], ['control [\"97956\"]', ['97956'], 'valid'], ['control [\"60866456\"]', ['60866456'], 'valid'], ['control [\"49717735275\"]', ['49717735275'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"9207919074163\"]', ['9207919074163'], 'valid'], ['control [\"470663048070284\"]', ['470663048070284'], 'valid'], ['control [\"2300017738893848\"]', ['2300017738893848'], 'valid'], ['control [\"7985145013991721\"]', ['7985145013991721'], 'valid'], ['control [\"067122965057139178\"]', ['067122965057139178'], 'valid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"1513156399001929628\"]', ['1513156399001929628'], 'valid'], ['control [\"9505094299844733505\"]', ['9505094299844733505'], 'valid'], ['control [\"0906050370970\"]', ['0906050370970'], 'valid'], ['control [\"3165356977\"]', ['3165356977'], 'valid'], ['control [\"91\"]', ['91'], 'valid']], [['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"992\"]', ['992'], 'valid'], ['control [\"5553\"]', ['5553'], 'valid'], ['control [\"77777779\"]', ['77777779'], 'valid'], ['control [\"52\"]', ['52'], 'invalid'], ['control [\"185\"]', ['185'], 'invalid']], [['regression [\"4111-1111-1111-1111\"]', ['4111-1111-1111-1111'], 'valid'], ['regression [\"4111-1111 1111-1112\"]', ['4111-1111 1111-1112'], 'invalid'], ['partial-repair [\"4111a1111\"]', ['4111a1111'], 'malformed'], ['control [\"97959\"]', ['97959'], 'invalid'], ['control [\"60866459\"]', ['60866459'], 'invalid'], ['control [\"49717735278\"]', ['49717735278'], 'invalid'], ['control [\"9207919074166\"]', ['9207919074166'], 'invalid'], ['control [\"470663048070287\"]', ['470663048070287'], 'invalid']]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\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":"A deterministic, bounded teaching model of the named scheme under the stated contract; not a certified validator. 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":"w2-check_digit_algorithms-luhn-validate-separator-normalization","generated_at":"2026-09-29T14:48:37.804136+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Payment-card, loyalty and account numbers are screened with the Luhn mod-10 check before any lookup.","repair":"Remove both spaces and hyphens, and nothing else, before the digit gate.","root_cause":"Only spaces are removed before validation; hyphens remain and fail the digit gate.","sha256":"54d43de9ee7ad688b0b430a9996fe878b2c900e96fcc0d29a8300cec18ec7b8e","title":"Luhn normalization keeps hyphen group separators · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.248,"exit_code":1,"observations":[{"actual":"valid","check":"regression [\"4111-1111-1111-1111\"]","expected":"valid","passed":true},{"actual":"invalid","check":"regression [\"4111-1111 1111-1112\"]","expected":"invalid","passed":true},{"actual":"invalid","check":"partial-repair [\"4111a1111\"]","expected":"malformed","passed":false},{"actual":"valid","check":"control [\"59\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"182\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"97956\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"60866456\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"49717735275\"]","expected":"valid","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [\\\"4111-1111-1111-1111\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"regression [\\\"4111-1111 1111-1112\\\"]\", \"actual\": \"invalid\", \"expected\": \"invalid\", \"passed\": true}, {\"check\": \"partial-repair [\\\"4111a1111\\\"]\", \"actual\": \"invalid\", \"expected\": \"malformed\", \"passed\": false}, {\"check\": \"control [\\\"59\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"182\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"97956\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"60866456\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"49717735275\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.068,"exit_code":1,"observations":[{"actual":"malformed","check":"regression [\"4111-1111-1111-1111\"]","expected":"valid","passed":false},{"actual":"malformed","check":"regression [\"4111-1111 1111-1112\"]","expected":"invalid","passed":false},{"actual":"malformed","check":"partial-repair [\"4111a1111\"]","expected":"malformed","passed":true},{"actual":"valid","check":"control [\"59\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"182\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"97956\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"60866456\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"49717735275\"]","expected":"valid","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [\\\"4111-1111-1111-1111\\\"]\", \"actual\": \"malformed\", \"expected\": \"valid\", \"passed\": false}, {\"check\": \"regression [\\\"4111-1111 1111-1112\\\"]\", \"actual\": \"malformed\", \"expected\": \"invalid\", \"passed\": false}, {\"check\": \"partial-repair [\\\"4111a1111\\\"]\", \"actual\": \"malformed\", \"expected\": \"malformed\", \"passed\": true}, {\"check\": \"control [\\\"59\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"182\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"97956\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"60866456\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"49717735275\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":37.448,"exit_code":0,"observations":[{"actual":"valid","check":"regression [\"4111-1111-1111-1111\"]","expected":"valid","passed":true},{"actual":"invalid","check":"regression [\"4111-1111 1111-1112\"]","expected":"invalid","passed":true},{"actual":"malformed","check":"partial-repair [\"4111a1111\"]","expected":"malformed","passed":true},{"actual":"valid","check":"control [\"59\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"182\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"97956\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"60866456\"]","expected":"valid","passed":true},{"actual":"valid","check":"control [\"49717735275\"]","expected":"valid","passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [\\\"4111-1111-1111-1111\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"regression [\\\"4111-1111 1111-1112\\\"]\", \"actual\": \"invalid\", \"expected\": \"invalid\", \"passed\": true}, {\"check\": \"partial-repair [\\\"4111a1111\\\"]\", \"actual\": \"malformed\", \"expected\": \"malformed\", \"passed\": true}, {\"check\": \"control [\\\"59\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"182\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"97956\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"60866456\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}, {\"check\": \"control [\\\"49717735275\\\"]\", \"actual\": \"valid\", \"expected\": \"valid\", \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}