FAILURE MAP
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FA-83181 / Go territory scoring / Open access

The button goes to the last player to pass · case 01

The ending pass, not the first pass, earns the half point.

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

ROOT CAUSE

The code inspects passes[-1].

THE FAILURE

The code inspects passes[-1].

Unsuccessful approach: Awarding it to whoever passed more often ignores the order of passes.

Case contract

Input [area_b, area_w, passes, komi_tenths]. The first player ever to pass takes the button worth half a point. Return [black_tenths, white_tenths, winner] with winner B, W or draw.

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):
    ab, aw, passes, komi = x
    sb = ab * 10
    sw = aw * 10 + komi
    if passes:
        if passes[-1] == 'B':
            sb += 5
        else:
            sw += 5
    winner = 'B' if sb > sw else 'W' if sw > sb else 'draw'
    return [sb, sw, winner]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[179, 170, ['W', 'B'], 0], [1790, 1705, 'B']], [[171, 180, ['W', 'B', 'B'], 60], [1710, 1865, 'W']], [[186, 187, ['B', 'W'], 0], [1865, 1870, 'W']], [[187, 178, ['W'], 60], [1870, 1845, 'B']], [[178, 183, ['W', 'W', 'W'], 60], [1780, 1895, 'W']], [[179, 185, ['W'], 60], [1790, 1915, 'W']], [[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']], [[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']]], [[[186, 187, ['B', 'W'], 0], [1865, 1870, 'W']], [[186, 183, [], 60], [1860, 1890, 'W']], [[191, 181, ['B', 'W', 'W'], 0], [1915, 1810, 'B']], [[186, 178, ['W', 'B'], 5], [1860, 1790, 'B']], [[187, 185, ['W'], 70], [1870, 1925, 'W']], [[178, 182, ['B', 'B'], 5], [1785, 1825, 'W']], [[176, 188, ['W', 'W'], 5], [1760, 1890, 'W']], [[176, 188, ['W', 'B'], 60], [1760, 1945, 'W']]], [[[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']], [[186, 178, ['W', 'B'], 5], [1860, 1790, 'B']], [[175, 191, [], 5], [1750, 1915, 'W']], [[186, 183, ['W', 'W', 'W'], 5], [1860, 1840, 'B']], [[170, 181, [], 0], [1700, 1810, 'W']], [[179, 175, ['W'], 60], [1790, 1815, 'W']], [[190, 180, ['B', 'W', 'W'], 70], [1905, 1870, 'B']], [[176, 182, ['W', 'W', 'W'], 70], [1760, 1895, 'W']]], [[[176, 182, ['W', 'W', 'W'], 70], [1760, 1895, 'W']], [[179, 189, [], 60], [1790, 1950, 'W']], [[172, 174, [], 5], [1720, 1745, 'W']], [[177, 171, ['W'], 70], [1770, 1785, 'W']], [[179, 182, ['B'], 0], [1795, 1820, 'W']], [[182, 174, ['B', 'B'], 70], [1825, 1810, 'B']], [[179, 175, ['W', 'W', 'B'], 60], [1790, 1815, 'W']], [[173, 178, ['W', 'B'], 70], [1730, 1855, 'W']]], [[[178, 189, ['W'], 0], [1780, 1895, 'W']], [[177, 171, ['B'], 60], [1775, 1770, 'B']], [[175, 176, ['B'], 5], [1755, 1765, 'W']], [[182, 185, ['B', 'W'], 60], [1825, 1910, 'W']], [[179, 175, ['W', 'W', 'B'], 60], [1790, 1815, 'W']], [[181, 180, ['B', 'B'], 70], [1815, 1870, 'W']], [[173, 178, ['W', 'B'], 70], [1730, 1855, 'W']], [[170, 179, ['W', 'B'], 5], [1700, 1800, 'W']]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("button 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
button case 0[1795, 1700, 'B'][1790, 1705, 'B']Failed
button case 1[1715, 1860, 'W'][1710, 1865, 'W']Failed
button case 2[1860, 1875, 'W'][1865, 1870, 'W']Failed
button case 3[1870, 1845, 'B'][1870, 1845, 'B']Passed
button case 4[1780, 1895, 'W'][1780, 1895, 'W']Passed
button case 5[1790, 1915, 'W'][1790, 1915, 'W']Passed
button case 6[1745, 1825, 'W'][1740, 1830, 'W']Failed
button case 7[1745, 1825, 'W'][1740, 1830, 'W']Failed

SHA-256 / 6560801d00d3d086f7392db7191931ae8a8b718c0a690076a18338b5a49b3a77

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    ab, aw, passes, komi = x
    sb = ab * 10
    sw = aw * 10 + komi
    if passes:
        if passes.count('B') >= passes.count('W'):
            sb += 5
        else:
            sw += 5
    winner = 'B' if sb > sw else 'W' if sw > sb else 'draw'
    return [sb, sw, winner]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[[179, 170, ['W', 'B'], 0], [1790, 1705, 'B']], [[171, 180, ['W', 'B', 'B'], 60], [1710, 1865, 'W']], [[186, 187, ['B', 'W'], 0], [1865, 1870, 'W']], [[187, 178, ['W'], 60], [1870, 1845, 'B']], [[178, 183, ['W', 'W', 'W'], 60], [1780, 1895, 'W']], [[179, 185, ['W'], 60], [1790, 1915, 'W']], [[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']], [[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']]], [[[186, 187, ['B', 'W'], 0], [1865, 1870, 'W']], [[186, 183, [], 60], [1860, 1890, 'W']], [[191, 181, ['B', 'W', 'W'], 0], [1915, 1810, 'B']], [[186, 178, ['W', 'B'], 5], [1860, 1790, 'B']], [[187, 185, ['W'], 70], [1870, 1925, 'W']], [[178, 182, ['B', 'B'], 5], [1785, 1825, 'W']], [[176, 188, ['W', 'W'], 5], [1760, 1890, 'W']], [[176, 188, ['W', 'B'], 60], [1760, 1945, 'W']]], [[[174, 182, ['W', 'B', 'B'], 5], [1740, 1830, 'W']], [[186, 178, ['W', 'B'], 5], [1860, 1790, 'B']], [[175, 191, [], 5], [1750, 1915, 'W']], [[186, 183, ['W', 'W', 'W'], 5], [1860, 1840, 'B']], [[170, 181, [], 0], [1700, 1810, 'W']], [[179, 175, ['W'], 60], [1790, 1815, 'W']], [[190, 180, ['B', 'W', 'W'], 70], [1905, 1870, 'B']], [[176, 182, ['W', 'W', 'W'], 70], [1760, 1895, 'W']]], [[[176, 182, ['W', 'W', 'W'], 70], [1760, 1895, 'W']], [[179, 189, [], 60], [1790, 1950, 'W']], [[172, 174, [], 5], [1720, 1745, 'W']], [[177, 171, ['W'], 70], [1770, 1785, 'W']], [[179, 182, ['B'], 0], [1795, 1820, 'W']], [[182, 174, ['B', 'B'], 70], [1825, 1810, 'B']], [[179, 175, ['W', 'W', 'B'], 60], [1790, 1815, 'W']], [[173, 178, ['W', 'B'], 70], [1730, 1855, 'W']]], [[[178, 189, ['W'], 0], [1780, 1895, 'W']], [[177, 171, ['B'], 60], [1775, 1770, 'B']], [[175, 176, ['B'], 5], [1755, 1765, 'W']], [[182, 185, ['B', 'W'], 60], [1825, 1910, 'W']], [[179, 175, ['W', 'W', 'B'], 60], [1790, 1815, 'W']], [[181, 180, ['B', 'B'], 70], [1815, 1870, 'W']], [[173, 178, ['W', 'B'], 70], [1730, 1855, 'W']], [[170, 179, ['W', 'B'], 5], [1700, 1800, 'W']]]]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("button 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
button case 0[1795, 1700, 'B'][1790, 1705, 'B']Failed
button case 1[1715, 1860, 'W'][1710, 1865, 'W']Failed
button case 2[1865, 1870, 'W'][1865, 1870, 'W']Passed
button case 3[1870, 1845, 'B'][1870, 1845, 'B']Passed
button case 4[1780, 1895, 'W'][1780, 1895, 'W']Passed
button case 5[1790, 1915, 'W'][1790, 1915, 'W']Passed
button case 6[1745, 1825, 'W'][1740, 1830, 'W']Failed
button case 7[1745, 1825, 'W'][1740, 1830, 'W']Failed

SHA-256 / ec4008ecb6705aa4195824cd15563a3038d39e3b8cbde2c2a8cae5244ab793cb

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

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 2026-09-29T14:50:19.327452+00:00.

Case digest / 12440f4c90459987ea067d4aa202111aa5ed088880f8d7a77074bebb5d201588