FAILURE MAP
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FA-83741 / Card game rule engines / Open access

Same-rank plays cannot beat each other by suit · case 01

5S cannot be played over 5D.

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

ROOT CAUSE

The comparison key ignores suits.

VERIFIED REPAIR

Break rank ties by suit D<C<H<S.

Unsuccessful approach: Alphabetical suit order puts clubs below diamonds.

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])
    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 = [[[[[], ['KD']], 'ok'], [[['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'], [[['9C'], ['9D']], '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'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['KC'], ['KD']], 'invalid']], [[[['9D', '9C'], ['9D', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['2H'], ['2S']], 'ok'], [[['5C'], ['5D']], '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'], [[['TD'], ['TS']], 'ok'], [[['9C'], ['9D']], 'invalid']], [[[['6C', '6H'], ['AH', '4D']], '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'], [[['9D', '9H', '9C'], ['9D', '9H', '9S']], 'ok'], [[['8D'], ['8C']], 'ok']]]
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 0okokPassed
play case 1invalidokFailed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6invalidokFailed
play case 7invalidinvalidPassed

SHA-256 / a0ae6016fe35b453291c9475fd3e7f74d845b325014cff30320f8c0a45284013

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 = 'CDHS'
    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 = [[[[[], ['KD']], 'ok'], [[['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'], [[['9C'], ['9D']], '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'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['KC'], ['KD']], 'invalid']], [[[['9D', '9C'], ['9D', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['2H'], ['2S']], 'ok'], [[['5C'], ['5D']], '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'], [[['TD'], ['TS']], 'ok'], [[['9C'], ['9D']], 'invalid']], [[[['6C', '6H'], ['AH', '4D']], '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'], [[['9D', '9H', '9C'], ['9D', '9H', '9S']], 'ok'], [[['8D'], ['8C']], 'ok']]]
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 0okokPassed
play case 1okokPassed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6okokPassed
play case 7okinvalidFailed

SHA-256 / 6932d6b7f88891cc6da012ee7c2d8c8bea029ba4b5c2f718ef4816e18cba2a9a

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 = [[[[[], ['KD']], 'ok'], [[['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'], [[['9C'], ['9D']], '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'], [[['3C', '3H'], ['3S', '3D']], 'ok'], [[['KC'], ['KD']], 'invalid']], [[[['9D', '9C'], ['9D', '9C']], 'invalid'], [[['KD'], ['AH']], 'ok'], [[[], ['KS', 'KD']], 'ok'], [[['JC'], ['7C']], 'invalid'], [[['5S'], ['5H']], 'invalid'], [[['2S'], ['5D']], 'invalid'], [[['2H'], ['2S']], 'ok'], [[['5C'], ['5D']], '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'], [[['TD'], ['TS']], 'ok'], [[['9C'], ['9D']], 'invalid']], [[[['6C', '6H'], ['AH', '4D']], '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'], [[['9D', '9H', '9C'], ['9D', '9H', '9S']], 'ok'], [[['8D'], ['8C']], 'ok']]]
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 0okokPassed
play case 1okokPassed
play case 2okokPassed
play case 3invalidinvalidPassed
play case 4invalidinvalidPassed
play case 5okokPassed
play case 6okokPassed
play case 7invalidinvalidPassed

SHA-256 / 331ad83e34e8f386b63d8f2a9b472acc3a79324c9fded1044a5a8dde4bf7eb1b

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 2026-09-29T14:50:24.536146+00:00.

Case digest / 17d046ee1754bac07e25ad1960a2312415e9cb6b87e058d40b0ab7f93af9b878