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FA-67261 / Railway interlocking logic / Open access

Sequential point throwing under a power budget: undetected point handling · case 01

A point without detection is assumed to lie correctly and is not thrown.

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

ROOT CAUSE

Missing detection is treated as already in position.

THE FAILURE

Missing detection is treated as already in position.

Unsuccessful approach: Defaulting the lookup to the needed lie makes the same assumption.

Case contract

A route needs points in given lies (processed in list order). Points already detected in the needed lie are skipped; an undetected point (missing from current) must be thrown. A point that must move but is locked by another route blocks the whole request (blocked:<p>, nothing thrown). At most max_parallel points move at once: each point starts on the earliest-free supply slot (lowest index on ties) and takes its own throw time or the default. Return the start time per thrown point and the time all have finished.

Why this case matters

Interlocking logic decides whether trains may be given authority; a wrong decision at this point either grants unsafe movements or strands traffic.

1 / The failure

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

N = 1
observations = []
def solve(x):
    cur = x['current']
    locked = set(x['locked'])
    todo = []
    for p, pos in x['need']:
        if p not in cur or cur[p] == pos:
            continue
        if p in locked:
            return {'result': 'blocked:' + p, 'starts': {}, 'done_s': 0}
        todo.append(p)
    slots = [0] * x['max_parallel']
    starts = {}
    for p in todo:
        k = min(range(len(slots)), key=lambda i: (slots[i], i))
        starts[p] = slots[k]
        slots[k] += x['throw_s'][p] if p in x['throw_s'] else x['default_throw_s']
    done = max(slots) if todo else 0
    return {'result': 'set', 'starts': starts, 'done_s': done}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 17', {'need': [['P2', 'N'], ['P5', 'N'], ['P4', 'N']], 'current': {'P1': 'R', 'P3': 'R', 'P4': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P1': 3, 'P3': 3, 'P5': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0, 'P5': 5}, 'done_s': 11}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('boundary: locked point already in the right lie', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0}, 'done_s': 5}), ('boundary: locked point needing to move', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 1', {'need': [['P3', 'R'], ['P6', 'N'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0, 'P6': 0, 'P1': 5}, 'done_s': 11}), ('control 4', {'need': [['P1', 'N'], ['P5', 'N']], 'current': {'P1': 'N', 'P2': 'R', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P3': 4, 'P5': 3, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('control 7', {'need': [['P6', 'R']], 'current': {'P1': 'R', 'P2': 'N', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P3': 3, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 57', {'need': [['P6', 'R'], ['P5', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'N', 'P5': 'N'}, 'locked': ['P2', 'P6'], 'max_parallel': 2, 'throw_s': {'P1': 4, 'P3': 3, 'P4': 3, 'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P6', 'starts': {}, 'done_s': 0}), ('sampled regression 31', {'need': [['P4', 'N'], ['P6', 'R'], ['P3', 'R'], ['P5', 'R'], ['P2', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 4, 'P4': 4, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 0, 'P3': 0, 'P5': 4}, 'done_s': 9}), ('boundary: three points on two supplies', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}, 'done_s': 8}), ('boundary: long first throw then short ones', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R'], ['P4', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3, 'P4': 6}, 'done_s': 9}), ('control 12', {'need': [['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P6'], 'max_parallel': 2, 'throw_s': {'P2': 6, 'P4': 3, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 18', {'need': [['P2', 'N'], ['P3', 'R']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P3': 6, 'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0, 'P3': 0}, 'done_s': 6})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 16', {'need': [['P4', 'R'], ['P2', 'N']], 'current': {'P1': 'N', 'P3': 'R', 'P4': 'N', 'P5': 'R', 'P6': 'R'}, 'locked': ['P6'], 'max_parallel': 3, 'throw_s': {'P1': 4, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P2': 0}, 'done_s': 3}), ('sampled regression 62', {'need': [['P6', 'N'], ['P5', 'N'], ['P1', 'N'], ['P2', 'N'], ['P4', 'N']], 'current': {'P3': 'R', 'P4': 'N', 'P5': 'N', 'P6': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 4, 'P2': 6, 'P3': 6, 'P4': 3, 'P5': 3, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 6}), ('boundary: long first throw then short ones', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R'], ['P4', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3, 'P4': 6}, 'done_s': 9}), ('boundary: single supply', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': [], 'max_parallel': 1, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 5}, 'done_s': 10}), ('sampled regression 23', {'need': [['P3', 'N'], ['P4', 'N'], ['P1', 'R'], ['P6', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P4': 3, 'P5': 4, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 3}, 'done_s': 6}), ('control 26', {'need': [['P1', 'N']], 'current': {'P1': 'N', 'P2': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P5', 'P6'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P3': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('sampled regression 29', {'need': [['P4', 'N'], ['P2', 'N'], ['P1', 'N'], ['P5', 'N'], ['P6', 'R']], 'current': {'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P1': 4, 'P2': 3, 'P3': 6, 'P4': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P1': 6}, 'done_s': 10})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 55', {'need': [['P3', 'R'], ['P2', 'R'], ['P6', 'N'], ['P1', 'N'], ['P5', 'R']], 'current': {'P1': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': ['P2', 'P5'], 'max_parallel': 1, 'throw_s': {'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P2', 'starts': {}, 'done_s': 0}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('boundary: nothing to move', {'need': [['P1', 'N']], 'current': {'P1': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('boundary: points with individual throw times', {'need': [['P4', 'R'], ['P5', 'N']], 'current': {'P4': 'N', 'P5': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P5': 3}, 'done_s': 8}), ('control 34', {'need': [['P3', 'R']], 'current': {'P1': 'R', 'P3': 'N', 'P4': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 6, 'P2': 3, 'P4': 4, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0}, 'done_s': 5}), ('control 37', {'need': [['P5', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P5': 'R'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P3': 6, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('control 40', {'need': [['P5', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 4, 'P2': 6, 'P3': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('sampled regression 31', {'need': [['P4', 'N'], ['P6', 'R'], ['P3', 'R'], ['P5', 'R'], ['P2', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 4, 'P4': 4, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 0, 'P3': 0, 'P5': 4}, 'done_s': 9}), ('boundary: locked point already in the right lie', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0}, 'done_s': 5}), ('boundary: locked point needing to move', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 45', {'need': [['P5', 'N'], ['P3', 'R'], ['P2', 'R'], ['P6', 'N'], ['P4', 'N']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P1', 'P2', 'P5'], 'max_parallel': 1, 'throw_s': {'P1': 6, 'P2': 4, 'P4': 6, 'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P2', 'starts': {}, 'done_s': 0}), ('control 48', {'need': [['P3', 'R']], 'current': {'P1': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P4'], 'max_parallel': 1, 'throw_s': {'P4': 6, 'P5': 6, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0}, 'done_s': 5}), ('control 51', {'need': [['P6', 'R'], ['P5', 'N'], ['P1', 'R'], ['P4', 'N']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 3, 'throw_s': {'P2': 6, 'P3': 6, 'P4': 6, 'P5': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})]]
for label, args, expected in fixtures[N-1]:
    check(label, 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
regression: undetected point{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}{'done_s': 5, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}Failed
sampled regression 17{'done_s': 6, 'result': 'set', 'starts': {'P5': 0}}{'done_s': 11, 'result': 'set', 'starts': {'P2': 0, 'P5': 5}}Failed
sampled regression 15{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}Failed
boundary: locked point already in the right lie{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}Passed
boundary: locked point needing to move{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}Passed
control 1{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}Passed
control 4{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'set', 'starts': {}}Passed
control 7{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'set', 'starts': {}}Passed

SHA-256 / bb4412a60a59b4ccc7444bc8e750cddf619fc6d37a761c39ee5562a1b8f175a2

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    cur = x['current']
    locked = set(x['locked'])
    todo = []
    for p, pos in x['need']:
        if cur.get(p, pos) == pos:
            continue
        if p in locked:
            return {'result': 'blocked:' + p, 'starts': {}, 'done_s': 0}
        todo.append(p)
    slots = [0] * x['max_parallel']
    starts = {}
    for p in todo:
        k = min(range(len(slots)), key=lambda i: (slots[i], i))
        starts[p] = slots[k]
        slots[k] += x['throw_s'][p] if p in x['throw_s'] else x['default_throw_s']
    done = max(slots) if todo else 0
    return {'result': 'set', 'starts': starts, 'done_s': done}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 17', {'need': [['P2', 'N'], ['P5', 'N'], ['P4', 'N']], 'current': {'P1': 'R', 'P3': 'R', 'P4': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P1': 3, 'P3': 3, 'P5': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0, 'P5': 5}, 'done_s': 11}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('boundary: locked point already in the right lie', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0}, 'done_s': 5}), ('boundary: locked point needing to move', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 1', {'need': [['P3', 'R'], ['P6', 'N'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0, 'P6': 0, 'P1': 5}, 'done_s': 11}), ('control 4', {'need': [['P1', 'N'], ['P5', 'N']], 'current': {'P1': 'N', 'P2': 'R', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P3': 4, 'P5': 3, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('control 7', {'need': [['P6', 'R']], 'current': {'P1': 'R', 'P2': 'N', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P3': 3, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 57', {'need': [['P6', 'R'], ['P5', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'N', 'P5': 'N'}, 'locked': ['P2', 'P6'], 'max_parallel': 2, 'throw_s': {'P1': 4, 'P3': 3, 'P4': 3, 'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P6', 'starts': {}, 'done_s': 0}), ('sampled regression 31', {'need': [['P4', 'N'], ['P6', 'R'], ['P3', 'R'], ['P5', 'R'], ['P2', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 4, 'P4': 4, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 0, 'P3': 0, 'P5': 4}, 'done_s': 9}), ('boundary: three points on two supplies', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}, 'done_s': 8}), ('boundary: long first throw then short ones', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R'], ['P4', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3, 'P4': 6}, 'done_s': 9}), ('control 12', {'need': [['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P6'], 'max_parallel': 2, 'throw_s': {'P2': 6, 'P4': 3, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 18', {'need': [['P2', 'N'], ['P3', 'R']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P3': 6, 'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0, 'P3': 0}, 'done_s': 6})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 16', {'need': [['P4', 'R'], ['P2', 'N']], 'current': {'P1': 'N', 'P3': 'R', 'P4': 'N', 'P5': 'R', 'P6': 'R'}, 'locked': ['P6'], 'max_parallel': 3, 'throw_s': {'P1': 4, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P2': 0}, 'done_s': 3}), ('sampled regression 62', {'need': [['P6', 'N'], ['P5', 'N'], ['P1', 'N'], ['P2', 'N'], ['P4', 'N']], 'current': {'P3': 'R', 'P4': 'N', 'P5': 'N', 'P6': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 4, 'P2': 6, 'P3': 6, 'P4': 3, 'P5': 3, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 6}), ('boundary: long first throw then short ones', {'need': [['P1', 'R'], ['P2', 'R'], ['P3', 'R'], ['P4', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P1': 6, 'P2': 3, 'P3': 3, 'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3, 'P4': 6}, 'done_s': 9}), ('boundary: single supply', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': [], 'max_parallel': 1, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 5}, 'done_s': 10}), ('sampled regression 23', {'need': [['P3', 'N'], ['P4', 'N'], ['P1', 'R'], ['P6', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P4': 3, 'P5': 4, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 3}, 'done_s': 6}), ('control 26', {'need': [['P1', 'N']], 'current': {'P1': 'N', 'P2': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P5', 'P6'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P3': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('sampled regression 29', {'need': [['P4', 'N'], ['P2', 'N'], ['P1', 'N'], ['P5', 'N'], ['P6', 'R']], 'current': {'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P1': 4, 'P2': 3, 'P3': 6, 'P4': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P1': 6}, 'done_s': 10})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 55', {'need': [['P3', 'R'], ['P2', 'R'], ['P6', 'N'], ['P1', 'N'], ['P5', 'R']], 'current': {'P1': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': ['P2', 'P5'], 'max_parallel': 1, 'throw_s': {'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P2', 'starts': {}, 'done_s': 0}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('boundary: nothing to move', {'need': [['P1', 'N']], 'current': {'P1': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0}), ('boundary: points with individual throw times', {'need': [['P4', 'R'], ['P5', 'N']], 'current': {'P4': 'N', 'P5': 'R'}, 'locked': [], 'max_parallel': 1, 'throw_s': {'P4': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P5': 3}, 'done_s': 8}), ('control 34', {'need': [['P3', 'R']], 'current': {'P1': 'R', 'P3': 'N', 'P4': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 6, 'P2': 3, 'P4': 4, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0}, 'done_s': 5}), ('control 37', {'need': [['P5', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P5': 'R'}, 'locked': [], 'max_parallel': 2, 'throw_s': {'P3': 6, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('control 40', {'need': [['P5', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 4, 'P2': 6, 'P3': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})], [('regression: undetected point', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P2': 'N'}, 'locked': [], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0, 'P2': 0}, 'done_s': 5}), ('sampled regression 15', {'need': [['P1', 'N'], ['P5', 'R'], ['P4', 'R'], ['P3', 'R'], ['P2', 'R']], 'current': {'P2': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'N'}, 'locked': ['P1', 'P4'], 'max_parallel': 1, 'throw_s': {'P2': 3, 'P5': 4}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('sampled regression 31', {'need': [['P4', 'N'], ['P6', 'R'], ['P3', 'R'], ['P5', 'R'], ['P2', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 4, 'P4': 4, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0, 'P6': 0, 'P3': 0, 'P5': 4}, 'done_s': 9}), ('boundary: locked point already in the right lie', {'need': [['P1', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P2': 0}, 'done_s': 5}), ('boundary: locked point needing to move', {'need': [['P1', 'R'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N'}, 'locked': ['P1'], 'max_parallel': 2, 'throw_s': {}, 'default_throw_s': 5}, {'result': 'blocked:P1', 'starts': {}, 'done_s': 0}), ('control 45', {'need': [['P5', 'N'], ['P3', 'R'], ['P2', 'R'], ['P6', 'N'], ['P4', 'N']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P1', 'P2', 'P5'], 'max_parallel': 1, 'throw_s': {'P1': 6, 'P2': 4, 'P4': 6, 'P5': 3}, 'default_throw_s': 5}, {'result': 'blocked:P2', 'starts': {}, 'done_s': 0}), ('control 48', {'need': [['P3', 'R']], 'current': {'P1': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'N', 'P6': 'N'}, 'locked': ['P4'], 'max_parallel': 1, 'throw_s': {'P4': 6, 'P5': 6, 'P6': 3}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0}, 'done_s': 5}), ('control 51', {'need': [['P6', 'R'], ['P5', 'N'], ['P1', 'R'], ['P4', 'N']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 3, 'throw_s': {'P2': 6, 'P3': 6, 'P4': 6, 'P5': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {}, 'done_s': 0})]]
for label, args, expected in fixtures[N-1]:
    check(label, 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
regression: undetected point{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}{'done_s': 5, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}Failed
sampled regression 17{'done_s': 6, 'result': 'set', 'starts': {'P5': 0}}{'done_s': 11, 'result': 'set', 'starts': {'P2': 0, 'P5': 5}}Failed
sampled regression 15{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}Failed
boundary: locked point already in the right lie{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}Passed
boundary: locked point needing to move{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}Passed
control 1{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}Passed
control 4{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'set', 'starts': {}}Passed
control 7{'done_s': 0, 'result': 'set', 'starts': {}}{'done_s': 0, 'result': 'set', 'starts': {}}Passed

SHA-256 / 4613923f57706701f15706c5b1dd8e4696da37619481da52d23a5928cb86b450

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.

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Verification & scope

Stipulated toy interlocking contract for a bounded teaching model; it makes no claim of conformance to any railway signalling standard and omits real safety cases. 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 2026-09-29T14:47:51.259877+00:00.

Case digest / 7d61a7d416482a3d2fc3ca356892fff1b77181bebf1b893bb7d80194e54aa60e