FAILURE MAP
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FA-83356 / Card game rule engines / Open access

Aces rank low in trick comparison · case 01

A led ace loses to a deuce of the same suit.

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

ROOT CAUSE

The rank string starts with A.

THE FAILURE

The rank string starts with A.

Unsuccessful approach: Reversing the rank string makes low cards win.

Case contract

Input [cards_in_play_order, leader_seat, trump_or_None, seats]. The highest trump wins; with no trump played the highest card of the led suit wins (A high). Off-suit non-trump cards never win. Return the winning seat, counting clockwise from the leader.

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):
    cards, leader, trump, seats = x
    order = 'A23456789TJQK'
    best = 0
    for i in range(1, len(cards)):
        card, top = cards[i], cards[best]
        if card[1] == top[1]:
            if order.index(card[0]) > order.index(top[0]):
                best = i
        elif card[1] == trump:
            best = i
    return (leader + best) % seats
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[['2H', '8D', 'TC', 'AH'], 2, 'S', 4], 1], [[['KC', 'AC', '8H', '8D'], 2, None, 4], 3], [[['3H', '9S', 'QD', '5H'], 3, 'D', 4], 1], [[['KD', '2H', '9D', '2D', '6C'], 4, None, 5], 4], [[['QH', '4D', 'TS', '5D', '2S'], 4, None, 5], 4], [[['8H', 'TS', '7D', 'JS'], 2, None, 4], 2], [[['8S', 'AD', 'KC'], 0, None, 3], 0], [[['9C', '7D', '8D', '2S', 'TD'], 4, 'D', 5], 3]], [[[['8C', '2C', '9D', '7C'], 1, None, 4], 1], [[['9C', '7D', '8D', '2S', 'TD'], 4, 'D', 5], 3], [[['JD', '2H', 'KD', '5D', 'QS'], 0, None, 5], 2], [[['2D', 'QC', '3S', '3H'], 3, 'S', 4], 1], [[['5C', '6H', '3C', 'AC'], 2, 'D', 4], 1], [[['4D', '6S', 'TH'], 2, 'D', 3], 2], [[['7H', '8D', 'AH', '5S', '6S'], 4, 'C', 5], 1], [[['TD', '5D', 'QS', 'AC', 'KS'], 1, None, 5], 1]], [[[['7H', '8D', 'AH', '5S', '6S'], 4, 'C', 5], 1], [[['5D', 'AD', '8H'], 1, None, 3], 2], [[['TD', '5D', 'QS', 'AC', 'KS'], 1, None, 5], 1], [[['8H', 'QC', 'JS'], 2, 'C', 3], 0], [[['KC', '6C', '4S'], 0, 'D', 3], 0], [[['3S', '6C', 'QS'], 0, 'S', 3], 2], [[['3D', 'QD', '8S', '6D', 'TS'], 2, None, 5], 3], [[['8C', '8S', 'AC'], 1, None, 3], 0]], [[[['8S', '5S', 'KS'], 2, 'H', 3], 1], [[['3D', 'QD', '8S', '6D', 'TS'], 2, None, 5], 3], [[['6D', '2H', '4D', '5S', '7S'], 4, 'H', 5], 0], [[['8C', '5H', '6H', '9C'], 2, None, 4], 1], [[['AH', 'TD', '4H', '3S', 'KD'], 1, None, 5], 1], [[['6H', 'AS', '7H', 'JD'], 2, 'D', 4], 1], [[['8C', '8S', 'AC'], 1, None, 3], 0], [[['QC', '9S', 'AC'], 1, None, 3], 0]], [[[['7S', '4S', '8D'], 1, 'S', 3], 1], [[['3S', 'JS', 'TC', '5D', '3H'], 2, 'D', 5], 0], [[['9H', '6H', '3D'], 1, 'S', 3], 1], [[['3H', '8D', '3C'], 0, 'H', 3], 0], [[['AD', 'JH', '8D', '5D'], 1, 'H', 4], 2], [[['8C', '8S', 'AC'], 1, None, 3], 0], [[['AH', '4H', '7S', 'JH'], 2, 'H', 4], 2], [[['5S', '8H', '4D', 'AS'], 0, 'S', 4], 3]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("trick 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
trick case 021Failed
trick case 123Failed
trick case 211Passed
trick case 344Passed
trick case 444Passed
trick case 522Passed
trick case 600Passed
trick case 733Passed

SHA-256 / e979083e03263de309ac2b9e15922bacde278116de983ef19b235a799aea28c9

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    cards, leader, trump, seats = x
    order = '23456789TJQKA'[::-1]
    best = 0
    for i in range(1, len(cards)):
        card, top = cards[i], cards[best]
        if card[1] == top[1]:
            if order.index(card[0]) > order.index(top[0]):
                best = i
        elif card[1] == trump:
            best = i
    return (leader + best) % seats
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[['2H', '8D', 'TC', 'AH'], 2, 'S', 4], 1], [[['KC', 'AC', '8H', '8D'], 2, None, 4], 3], [[['3H', '9S', 'QD', '5H'], 3, 'D', 4], 1], [[['KD', '2H', '9D', '2D', '6C'], 4, None, 5], 4], [[['QH', '4D', 'TS', '5D', '2S'], 4, None, 5], 4], [[['8H', 'TS', '7D', 'JS'], 2, None, 4], 2], [[['8S', 'AD', 'KC'], 0, None, 3], 0], [[['9C', '7D', '8D', '2S', 'TD'], 4, 'D', 5], 3]], [[[['8C', '2C', '9D', '7C'], 1, None, 4], 1], [[['9C', '7D', '8D', '2S', 'TD'], 4, 'D', 5], 3], [[['JD', '2H', 'KD', '5D', 'QS'], 0, None, 5], 2], [[['2D', 'QC', '3S', '3H'], 3, 'S', 4], 1], [[['5C', '6H', '3C', 'AC'], 2, 'D', 4], 1], [[['4D', '6S', 'TH'], 2, 'D', 3], 2], [[['7H', '8D', 'AH', '5S', '6S'], 4, 'C', 5], 1], [[['TD', '5D', 'QS', 'AC', 'KS'], 1, None, 5], 1]], [[[['7H', '8D', 'AH', '5S', '6S'], 4, 'C', 5], 1], [[['5D', 'AD', '8H'], 1, None, 3], 2], [[['TD', '5D', 'QS', 'AC', 'KS'], 1, None, 5], 1], [[['8H', 'QC', 'JS'], 2, 'C', 3], 0], [[['KC', '6C', '4S'], 0, 'D', 3], 0], [[['3S', '6C', 'QS'], 0, 'S', 3], 2], [[['3D', 'QD', '8S', '6D', 'TS'], 2, None, 5], 3], [[['8C', '8S', 'AC'], 1, None, 3], 0]], [[[['8S', '5S', 'KS'], 2, 'H', 3], 1], [[['3D', 'QD', '8S', '6D', 'TS'], 2, None, 5], 3], [[['6D', '2H', '4D', '5S', '7S'], 4, 'H', 5], 0], [[['8C', '5H', '6H', '9C'], 2, None, 4], 1], [[['AH', 'TD', '4H', '3S', 'KD'], 1, None, 5], 1], [[['6H', 'AS', '7H', 'JD'], 2, 'D', 4], 1], [[['8C', '8S', 'AC'], 1, None, 3], 0], [[['QC', '9S', 'AC'], 1, None, 3], 0]], [[[['7S', '4S', '8D'], 1, 'S', 3], 1], [[['3S', 'JS', 'TC', '5D', '3H'], 2, 'D', 5], 0], [[['9H', '6H', '3D'], 1, 'S', 3], 1], [[['3H', '8D', '3C'], 0, 'H', 3], 0], [[['AD', 'JH', '8D', '5D'], 1, 'H', 4], 2], [[['8C', '8S', 'AC'], 1, None, 3], 0], [[['AH', '4H', '7S', 'JH'], 2, 'H', 4], 2], [[['5S', '8H', '4D', 'AS'], 0, 'S', 4], 3]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("trick 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
trick case 021Failed
trick case 123Failed
trick case 211Passed
trick case 324Failed
trick case 444Passed
trick case 522Passed
trick case 600Passed
trick case 703Failed

SHA-256 / 0552911381516ff0bf7370497291afc2f64fb4bdd8acaf2672c88aea82c011fc

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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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 2026-09-29T14:50:20.746035+00:00.

Case digest / 9cb1b30a1123bc584e8286258114f4ab9adeaf4d664f532c3916bf72fc136019