FAILURE MAP
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FA-83746 / Card game rule engines / Open access

A single can beat a pair · case 01

Plays of a different size are compared by rank alone.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The same-size requirement is missing.

VERIFIED REPAIR

A response must have the same number of cards.

Unsuccessful approach: Allowing larger combinations over smaller ones still breaks the same-size rule.

Case contract

Input [current_combination, play]. Ranks 3 low to 2 high; suits D<C<H<S. A play is 1-3 cards of one rank. On an empty table any valid play is "ok"; otherwise it must have the same size and its highest card must outrank the current highest card (rank, then suit). Empty play is "pass". Return "ok", "invalid" or "pass".

Why this case matters

Card-game engines, scoring apps and online tables apply this rule automatically on every hand.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    cur, play = x
    order = '3456789TJQKA2'
    suits = 'DCHS'
    def key(c):
        return (order.index(c[0]), suits.index(c[1]))
    if not play:
        return 'pass'
    if len(set(c[0] for c in play)) != 1 or len(play) > 3:
        return 'invalid'
    if not cur:
        return 'ok'
    if max(key(c) for c in play) > max(key(c) for c in cur):
        return 'ok'
    return 'invalid'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[['7S'], ['9S', '9C']], 'invalid'], [[['KC', 'KD'], ['KH', 'KS']], 'ok'], [[['8S', '8C', '8H'], ['KD', 'KC', 'KS']], 'ok'], [[['6S'], ['6H']], 'invalid'], [[['9C'], ['6S']], 'invalid'], [[[], ['3H', '3S', '3C']], 'ok'], [[['7D'], ['7S']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['8D', '8H'], ['8S', '8D', '8H', '8C']], 'invalid'], [[['AS'], ['AH', 'AC', 'AD']], 'invalid'], [[[], ['3C']], 'ok'], [[['QD'], ['QH']], 'ok'], [[['JD', 'JS'], ['TD', 'TS', 'TC', 'TH']], 'invalid'], [[['9S', '9H'], ['8S', '8C']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['JH', 'JC'], ['JC', 'JS']], 'ok'], [[['7C'], ['2D']], 'ok'], [[['2H'], ['2H']], 'invalid'], [[['TH', 'TD'], ['8D', '2S']], 'invalid'], [[['5H', '5D'], ['JS', 'JC']], 'ok'], [[[], ['QC', 'QH']], 'ok'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['3D', '3H', '3C'], ['3S', '3D', '3H', 'AC']], 'invalid'], [[['5S'], ['3S']], 'invalid'], [[['9C'], ['9C']], 'invalid'], [[['7C', '7S', '7D'], ['3D', '3S', '3C']], 'invalid'], [[['3H', '3C'], ['3D', '3C', '3S', '3H']], 'invalid'], [[[], ['5H']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("play case %d" % i, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
play case 0okinvalidFailed
play case 1okokPassed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6okokPassed
play case 7okinvalidFailed

SHA-256 / c02f4351c34204fa44ed1f183fcec6ebcbcfad0b5c2a2be1eecc6c1e74cd0fd2

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    cur, play = x
    order = '3456789TJQKA2'
    suits = 'DCHS'
    def key(c):
        return (order.index(c[0]), suits.index(c[1]))
    if not play:
        return 'pass'
    if len(set(c[0] for c in play)) != 1 or len(play) > 3:
        return 'invalid'
    if not cur:
        return 'ok'
    if len(play) < len(cur):
        return 'invalid'
    if max(key(c) for c in play) > max(key(c) for c in cur):
        return 'ok'
    return 'invalid'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[['7S'], ['9S', '9C']], 'invalid'], [[['KC', 'KD'], ['KH', 'KS']], 'ok'], [[['8S', '8C', '8H'], ['KD', 'KC', 'KS']], 'ok'], [[['6S'], ['6H']], 'invalid'], [[['9C'], ['6S']], 'invalid'], [[[], ['3H', '3S', '3C']], 'ok'], [[['7D'], ['7S']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['8D', '8H'], ['8S', '8D', '8H', '8C']], 'invalid'], [[['AS'], ['AH', 'AC', 'AD']], 'invalid'], [[[], ['3C']], 'ok'], [[['QD'], ['QH']], 'ok'], [[['JD', 'JS'], ['TD', 'TS', 'TC', 'TH']], 'invalid'], [[['9S', '9H'], ['8S', '8C']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['JH', 'JC'], ['JC', 'JS']], 'ok'], [[['7C'], ['2D']], 'ok'], [[['2H'], ['2H']], 'invalid'], [[['TH', 'TD'], ['8D', '2S']], 'invalid'], [[['5H', '5D'], ['JS', 'JC']], 'ok'], [[[], ['QC', 'QH']], 'ok'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['3D', '3H', '3C'], ['3S', '3D', '3H', 'AC']], 'invalid'], [[['5S'], ['3S']], 'invalid'], [[['9C'], ['9C']], 'invalid'], [[['7C', '7S', '7D'], ['3D', '3S', '3C']], 'invalid'], [[['3H', '3C'], ['3D', '3C', '3S', '3H']], 'invalid'], [[[], ['5H']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("play case %d" % i, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
play case 0okinvalidFailed
play case 1okokPassed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6okokPassed
play case 7okinvalidFailed

SHA-256 / e8591d0cd1651cc00f83e0c0abb35a54556b0ba072d309b283fe110bf4ac88dd

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    cur, play = x
    order = '3456789TJQKA2'
    suits = 'DCHS'
    def key(c):
        return (order.index(c[0]), suits.index(c[1]))
    if not play:
        return 'pass'
    if len(set(c[0] for c in play)) != 1 or len(play) > 3:
        return 'invalid'
    if not cur:
        return 'ok'
    if len(play) != len(cur):
        return 'invalid'
    if max(key(c) for c in play) > max(key(c) for c in cur):
        return 'ok'
    return 'invalid'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[['7S'], ['9S', '9C']], 'invalid'], [[['KC', 'KD'], ['KH', 'KS']], 'ok'], [[['8S', '8C', '8H'], ['KD', 'KC', 'KS']], 'ok'], [[['6S'], ['6H']], 'invalid'], [[['9C'], ['6S']], 'invalid'], [[[], ['3H', '3S', '3C']], 'ok'], [[['7D'], ['7S']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['8D', '8H'], ['8S', '8D', '8H', '8C']], 'invalid'], [[['AS'], ['AH', 'AC', 'AD']], 'invalid'], [[[], ['3C']], 'ok'], [[['QD'], ['QH']], 'ok'], [[['JD', 'JS'], ['TD', 'TS', 'TC', 'TH']], 'invalid'], [[['9S', '9H'], ['8S', '8C']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid'], [[['9C'], ['TD', 'TS']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']], [[[['JH', 'JC'], ['JC', 'JS']], 'ok'], [[['7C'], ['2D']], 'ok'], [[['2H'], ['2H']], 'invalid'], [[['TH', 'TD'], ['8D', '2S']], 'invalid'], [[['5H', '5D'], ['JS', 'JC']], 'ok'], [[[], ['QC', 'QH']], 'ok'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid'], [[['QH'], ['QS', 'QH', 'QC']], 'invalid']], [[[['7S'], ['9S', '9C']], 'invalid'], [[['3D', '3H', '3C'], ['3S', '3D', '3H', 'AC']], 'invalid'], [[['5S'], ['3S']], 'invalid'], [[['9C'], ['9C']], 'invalid'], [[['7C', '7S', '7D'], ['3D', '3S', '3C']], 'invalid'], [[['3H', '3C'], ['3D', '3C', '3S', '3H']], 'invalid'], [[[], ['5H']], 'ok'], [[['6S'], ['2S', '2H', '2C']], 'invalid']]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("play case %d" % i, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
play case 0invalidinvalidPassed
play case 1okokPassed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6okokPassed
play case 7invalidinvalidPassed

SHA-256 / 91ea2439311766145b9346b2b141ecf2f12bd35a8a7021aa173cb40321c336cb

Verification & scope

A bounded toy rule contract stated explicitly in the contract field; cards are two-character codes (rank, suit). Not a complete implementation of any published rulebook or casino table rules. 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.

Observations recorded using Python 3.12.14 at 2026-09-29T14:50:24.578959+00:00.

Case digest / 6fe74317ca32be1013b94514d50e5dc64e9e7687e7e2a83dee091ec79d7c2c34