FA-83226 / Go territory scoring / Open access

Non-consecutive passes end the game · case 01

A pass, a move, then an opponent pass is treated as two consecutive passes.

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

ROOT CAUSE

Board moves do not clear the pending pass.

VERIFIED REPAIR

Clear the pending pass after any board move.

Unsuccessful approach: Clearing only when the passer moves again leaves the pass pending across an opponent move.

Case contract

Input list of "C:action" tokens. Two consecutive passes by different players end the game ["score", None, index]; any board move clears a pending pass; "resign"/"timeout" end it with the opponent as winner ["resign"/"time", winner, index]. Otherwise ["playing", None, len(moves)].

Why this case matters

Go servers and scoring tools compute this value automatically; a wrong answer changes a game result.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(x):
    moves = x
    prev_pass = None
    for idx, mv in enumerate(moves):
        who, _, act = mv.partition(':')
        other = 'W' if who == 'B' else 'B'
        if act == 'resign':
            return ['resign', other, idx]
        if act == 'timeout':
            return ['time', other, idx]
        if act == 'pass':
            if prev_pass is not None and prev_pass != who:
                return ['score', None, idx]
            prev_pass = who
    return ['playing', None, len(moves)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[], ['playing', None, 0]], [['B:resign', 'W:pass', 'W:resign', 'B:resign', 'B:qq', 'W:cc'], ['resign', 'W', 0]], [['B:timeout', 'W:pass', 'B:cc', 'B:cc'], ['time', 'W', 0]], [['B:timeout', 'W:pass', 'W:pass', 'W:pass'], ['time', 'W', 0]], [['B:timeout', 'W:cc'], ['time', 'W', 0]], [['B:timeout', 'W:resign'], ['time', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]]], [[['B:pass', 'W:dd'], ['playing', None, 2]], [['W:cc', 'B:pass', 'B:dd', 'W:cc', 'B:resign'], ['resign', 'W', 4]], [['B:pass'], ['playing', None, 1]], [['B:resign'], ['resign', 'W', 0]], [['B:resign', 'B:cc', 'W:timeout', 'W:pass', 'B:cc'], ['resign', 'W', 0]], [['B:cc', 'W:pass', 'B:dd', 'B:resign'], ['resign', 'W', 3]], [['B:pass', 'W:dd', 'B:cc', 'W:pass'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:qq'], ['playing', None, 2]], [['B:resign', 'W:pass'], ['resign', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:qq'], ['playing', None, 2]], [['B:pass', 'B:dd', 'B:qq'], ['playing', None, 3]], [['W:pass'], ['playing', None, 1]], [['B:qq', 'W:cc', 'B:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'B:dd', 'W:pass'], ['playing', None, 3]]], [[['B:resign', 'W:pass', 'B:pass', 'W:dd'], ['resign', 'W', 0]], [['B:pass', 'W:qq', 'B:resign', 'W:pass', 'B:resign'], ['resign', 'W', 2]], [['B:dd', 'W:pass', 'B:pass', 'W:cc', 'B:cc'], ['score', None, 2]], [['B:dd', 'W:resign', 'B:dd', 'W:dd'], ['resign', 'B', 1]], [['W:qq', 'W:timeout', 'B:dd', 'W:pass', 'B:cc', 'W:qq'], ['time', 'B', 1]], [['B:dd'], ['playing', None, 1]], [['B:pass', 'B:cc', 'B:cc', 'W:pass', 'W:cc', 'W:pass'], ['playing', None, 6]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:dd', 'B:cc', 'B:cc', 'W:resign'], ['resign', 'B', 3]], [['W:pass', 'B:timeout', 'B:cc', 'W:dd'], ['time', 'W', 1]], [['B:timeout'], ['time', 'W', 0]], [['B:pass', 'W:pass', 'B:pass', 'W:resign', 'B:pass', 'W:dd'], ['score', None, 1]], [['W:timeout', 'W:cc', 'B:cc', 'W:pass', 'B:dd', 'W:qq'], ['time', 'B', 0]], [['B:pass', 'W:resign', 'W:pass'], ['resign', 'B', 1]], [['W:pass', 'W:qq', 'B:dd', 'W:cc', 'B:pass', 'B:dd'], ['playing', None, 6]]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("game end 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 fixture	Actual	Expected	Outcome
game end case 0	`['playing', None, 0]`	`['playing', None, 0]`	Passed
game end case 1	`['resign', 'W', 0]`	`['resign', 'W', 0]`	Passed
game end case 2	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 3	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 4	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 5	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 6	`['score', None, 2]`	`['playing', None, 4]`	Failed
game end case 7	`['score', None, 2]`	`['playing', None, 4]`	Failed

SHA-256 / 2820741ed566aad0f0c2caa122aceade49446b6c5b56d3b49dd719350ac00544

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    moves = x
    prev_pass = None
    for idx, mv in enumerate(moves):
        who, _, act = mv.partition(':')
        other = 'W' if who == 'B' else 'B'
        if act == 'resign':
            return ['resign', other, idx]
        if act == 'timeout':
            return ['time', other, idx]
        if act == 'pass':
            if prev_pass is not None and prev_pass != who:
                return ['score', None, idx]
            prev_pass = who
        else:
            prev_pass = None if who == prev_pass else prev_pass
    return ['playing', None, len(moves)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[], ['playing', None, 0]], [['B:resign', 'W:pass', 'W:resign', 'B:resign', 'B:qq', 'W:cc'], ['resign', 'W', 0]], [['B:timeout', 'W:pass', 'B:cc', 'B:cc'], ['time', 'W', 0]], [['B:timeout', 'W:pass', 'W:pass', 'W:pass'], ['time', 'W', 0]], [['B:timeout', 'W:cc'], ['time', 'W', 0]], [['B:timeout', 'W:resign'], ['time', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]]], [[['B:pass', 'W:dd'], ['playing', None, 2]], [['W:cc', 'B:pass', 'B:dd', 'W:cc', 'B:resign'], ['resign', 'W', 4]], [['B:pass'], ['playing', None, 1]], [['B:resign'], ['resign', 'W', 0]], [['B:resign', 'B:cc', 'W:timeout', 'W:pass', 'B:cc'], ['resign', 'W', 0]], [['B:cc', 'W:pass', 'B:dd', 'B:resign'], ['resign', 'W', 3]], [['B:pass', 'W:dd', 'B:cc', 'W:pass'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:qq'], ['playing', None, 2]], [['B:resign', 'W:pass'], ['resign', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:qq'], ['playing', None, 2]], [['B:pass', 'B:dd', 'B:qq'], ['playing', None, 3]], [['W:pass'], ['playing', None, 1]], [['B:qq', 'W:cc', 'B:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'B:dd', 'W:pass'], ['playing', None, 3]]], [[['B:resign', 'W:pass', 'B:pass', 'W:dd'], ['resign', 'W', 0]], [['B:pass', 'W:qq', 'B:resign', 'W:pass', 'B:resign'], ['resign', 'W', 2]], [['B:dd', 'W:pass', 'B:pass', 'W:cc', 'B:cc'], ['score', None, 2]], [['B:dd', 'W:resign', 'B:dd', 'W:dd'], ['resign', 'B', 1]], [['W:qq', 'W:timeout', 'B:dd', 'W:pass', 'B:cc', 'W:qq'], ['time', 'B', 1]], [['B:dd'], ['playing', None, 1]], [['B:pass', 'B:cc', 'B:cc', 'W:pass', 'W:cc', 'W:pass'], ['playing', None, 6]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:dd', 'B:cc', 'B:cc', 'W:resign'], ['resign', 'B', 3]], [['W:pass', 'B:timeout', 'B:cc', 'W:dd'], ['time', 'W', 1]], [['B:timeout'], ['time', 'W', 0]], [['B:pass', 'W:pass', 'B:pass', 'W:resign', 'B:pass', 'W:dd'], ['score', None, 1]], [['W:timeout', 'W:cc', 'B:cc', 'W:pass', 'B:dd', 'W:qq'], ['time', 'B', 0]], [['B:pass', 'W:resign', 'W:pass'], ['resign', 'B', 1]], [['W:pass', 'W:qq', 'B:dd', 'W:cc', 'B:pass', 'B:dd'], ['playing', None, 6]]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("game end 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 fixture	Actual	Expected	Outcome
game end case 0	`['playing', None, 0]`	`['playing', None, 0]`	Passed
game end case 1	`['resign', 'W', 0]`	`['resign', 'W', 0]`	Passed
game end case 2	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 3	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 4	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 5	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 6	`['score', None, 2]`	`['playing', None, 4]`	Failed
game end case 7	`['score', None, 2]`	`['playing', None, 4]`	Failed

SHA-256 / 77b047769b6adf176bd173ab2586e2706c25f303120df9b6ab4e12ac4b1c7d02

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    moves = x
    prev_pass = None
    for idx, mv in enumerate(moves):
        who, _, act = mv.partition(':')
        other = 'W' if who == 'B' else 'B'
        if act == 'resign':
            return ['resign', other, idx]
        if act == 'timeout':
            return ['time', other, idx]
        if act == 'pass':
            if prev_pass is not None and prev_pass != who:
                return ['score', None, idx]
            prev_pass = who
        else:
            prev_pass = None
    return ['playing', None, len(moves)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[], ['playing', None, 0]], [['B:resign', 'W:pass', 'W:resign', 'B:resign', 'B:qq', 'W:cc'], ['resign', 'W', 0]], [['B:timeout', 'W:pass', 'B:cc', 'B:cc'], ['time', 'W', 0]], [['B:timeout', 'W:pass', 'W:pass', 'W:pass'], ['time', 'W', 0]], [['B:timeout', 'W:cc'], ['time', 'W', 0]], [['B:timeout', 'W:resign'], ['time', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]]], [[['B:pass', 'W:dd'], ['playing', None, 2]], [['W:cc', 'B:pass', 'B:dd', 'W:cc', 'B:resign'], ['resign', 'W', 4]], [['B:pass'], ['playing', None, 1]], [['B:resign'], ['resign', 'W', 0]], [['B:resign', 'B:cc', 'W:timeout', 'W:pass', 'B:cc'], ['resign', 'W', 0]], [['B:cc', 'W:pass', 'B:dd', 'B:resign'], ['resign', 'W', 3]], [['B:pass', 'W:dd', 'B:cc', 'W:pass'], ['playing', None, 4]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:qq'], ['playing', None, 2]], [['B:resign', 'W:pass'], ['resign', 'W', 0]], [['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'W:qq'], ['playing', None, 2]], [['B:pass', 'B:dd', 'B:qq'], ['playing', None, 3]], [['W:pass'], ['playing', None, 1]], [['B:qq', 'W:cc', 'B:pass', 'B:cc'], ['playing', None, 4]], [['B:pass', 'B:dd', 'W:pass'], ['playing', None, 3]]], [[['B:resign', 'W:pass', 'B:pass', 'W:dd'], ['resign', 'W', 0]], [['B:pass', 'W:qq', 'B:resign', 'W:pass', 'B:resign'], ['resign', 'W', 2]], [['B:dd', 'W:pass', 'B:pass', 'W:cc', 'B:cc'], ['score', None, 2]], [['B:dd', 'W:resign', 'B:dd', 'W:dd'], ['resign', 'B', 1]], [['W:qq', 'W:timeout', 'B:dd', 'W:pass', 'B:cc', 'W:qq'], ['time', 'B', 1]], [['B:dd'], ['playing', None, 1]], [['B:pass', 'B:cc', 'B:cc', 'W:pass', 'W:cc', 'W:pass'], ['playing', None, 6]], [['B:pass', 'W:cc', 'W:pass', 'W:timeout', 'B:qq'], ['time', 'B', 3]]], [[['B:pass', 'W:cc', 'W:pass', 'B:cc'], ['playing', None, 4]], [['B:dd', 'B:cc', 'B:cc', 'W:resign'], ['resign', 'B', 3]], [['W:pass', 'B:timeout', 'B:cc', 'W:dd'], ['time', 'W', 1]], [['B:timeout'], ['time', 'W', 0]], [['B:pass', 'W:pass', 'B:pass', 'W:resign', 'B:pass', 'W:dd'], ['score', None, 1]], [['W:timeout', 'W:cc', 'B:cc', 'W:pass', 'B:dd', 'W:qq'], ['time', 'B', 0]], [['B:pass', 'W:resign', 'W:pass'], ['resign', 'B', 1]], [['W:pass', 'W:qq', 'B:dd', 'W:cc', 'B:pass', 'B:dd'], ['playing', None, 6]]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("game end 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 fixture	Actual	Expected	Outcome
game end case 0	`['playing', None, 0]`	`['playing', None, 0]`	Passed
game end case 1	`['resign', 'W', 0]`	`['resign', 'W', 0]`	Passed
game end case 2	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 3	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 4	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 5	`['time', 'W', 0]`	`['time', 'W', 0]`	Passed
game end case 6	`['playing', None, 4]`	`['playing', None, 4]`	Passed
game end case 7	`['playing', None, 4]`	`['playing', None, 4]`	Passed

SHA-256 / 0e484a3fed46a42ba5bc351b36dd96c7e782b4cc24e3ae8011902d32b9fa4527

Verification & scope

Small rectangular toy boards given as strings of B, W and dot; a bounded teaching model of one scoring or bookkeeping rule, not a complete rules engine or server implementation. 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 2026-09-29T14:50:19.538976+00:00.

Case digest / 99c3b20a29816fcd393493a1556d870304d40e72ce2dab2903195ad329a43bec