FA-67256 / Railway interlocking logic / Open access

Sequential point throwing under a power budget: completion time · case 01

The route is reported ready at the wrong time.

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

ROOT CAUSE

Parallel supply slots are added up as if they ran sequentially.

THE FAILURE

Parallel supply slots are added up as if they ran sequentially.

Unsuccessful approach: Using the last start time forgets the duration of the final throw.

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 cur.get(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 = sum(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}), ('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}), ('sampled regression 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}), ('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}), ('regression: 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}), ('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}), ('control 10', {'need': [['P3', 'R'], ['P4', 'N']], 'current': {'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': ['P1', 'P5'], 'max_parallel': 3, 'throw_s': {'P2': 3, 'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0}, 'done_s': 4})], [('regression: 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}), ('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 30', {'need': [['P6', 'N'], ['P5', 'R'], ['P3', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 3, 'P4': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P6': 0, 'P1': 0}, 'done_s': 6}), ('sampled regression 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}), ('regression: 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}), ('control 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 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: 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}), ('regression: 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}), ('sampled regression 76', {'need': [['P3', 'R'], ['P5', 'N'], ['P6', 'R']], 'current': {'P1': 'R', 'P2': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': ['P2'], 'max_parallel': 3, 'throw_s': {'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0, 'P5': 0, 'P6': 0}, 'done_s': 5}), ('control 8', {'need': [['P3', 'R'], ['P1', 'N'], ['P6', 'R']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('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}), ('control 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}), ('control 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}), ('regression: 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}), ('sampled regression 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}), ('sampled regression 13', {'need': [['P5', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 3, 'P3': 6, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P5': 0, 'P2': 0}, 'done_s': 5}), ('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}), ('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: 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: 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 30', {'need': [['P6', 'N'], ['P5', 'R'], ['P3', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 3, 'P4': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P6': 0, 'P1': 0}, 'done_s': 6}), ('control 20', {'need': [['P6', 'N'], ['P5', 'N'], ['P2', 'N'], ['P4', 'R']], 'current': {'P2': 'N', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 6, 'P2': 4, 'P4': 6, 'P5': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0}, 'done_s': 6}), ('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}), ('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 fixture	Actual	Expected	Outcome
regression: undetected point	`{'done_s': 10, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}`	`{'done_s': 5, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}`	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
sampled regression 1	`{'done_s': 16, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}`	`{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}`	Failed
boundary: locked point needing to move	`{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}`	`{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}`	Passed
regression: three points on two supplies	`{'done_s': 14, 'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}}`	`{'done_s': 8, 'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}}`	Failed
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
control 10	`{'done_s': 4, 'result': 'set', 'starts': {'P4': 0}}`	`{'done_s': 4, 'result': 'set', 'starts': {'P4': 0}}`	Passed

SHA-256 / 34d7fdd2fd39735fe51258fc80dcd3998a5b5d4e0b84c4d99996fdc91cff4b9e

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:
            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(starts.values()) 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}), ('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}), ('sampled regression 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}), ('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}), ('regression: 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}), ('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}), ('control 10', {'need': [['P3', 'R'], ['P4', 'N']], 'current': {'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'N', 'P6': 'R'}, 'locked': ['P1', 'P5'], 'max_parallel': 3, 'throw_s': {'P2': 3, 'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0}, 'done_s': 4})], [('regression: 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}), ('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 30', {'need': [['P6', 'N'], ['P5', 'R'], ['P3', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 3, 'P4': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P6': 0, 'P1': 0}, 'done_s': 6}), ('sampled regression 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}), ('regression: 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}), ('control 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 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: 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}), ('regression: 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}), ('sampled regression 76', {'need': [['P3', 'R'], ['P5', 'N'], ['P6', 'R']], 'current': {'P1': 'R', 'P2': 'N', 'P5': 'R', 'P6': 'N'}, 'locked': ['P2'], 'max_parallel': 3, 'throw_s': {'P2': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P3': 0, 'P5': 0, 'P6': 0}, 'done_s': 5}), ('control 8', {'need': [['P3', 'R'], ['P1', 'N'], ['P6', 'R']], 'current': {'P1': 'R', 'P2': 'R', 'P3': 'R', 'P6': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P4': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P1': 0}, 'done_s': 5}), ('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}), ('control 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}), ('control 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}), ('regression: 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}), ('sampled regression 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}), ('sampled regression 13', {'need': [['P5', 'N'], ['P2', 'R']], 'current': {'P1': 'N', 'P2': 'N', 'P3': 'N', 'P4': 'R', 'P5': 'R'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 3, 'P2': 3, 'P3': 6, 'P6': 4}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P5': 0, 'P2': 0}, 'done_s': 5}), ('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}), ('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: 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: 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 30', {'need': [['P6', 'N'], ['P5', 'R'], ['P3', 'R'], ['P1', 'N']], 'current': {'P1': 'R', 'P2': 'N', 'P3': 'R', 'P4': 'R', 'P5': 'R', 'P6': 'R'}, 'locked': ['P3'], 'max_parallel': 2, 'throw_s': {'P1': 3, 'P2': 6, 'P3': 3, 'P4': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P6': 0, 'P1': 0}, 'done_s': 6}), ('control 20', {'need': [['P6', 'N'], ['P5', 'N'], ['P2', 'N'], ['P4', 'R']], 'current': {'P2': 'N', 'P3': 'N', 'P4': 'N', 'P5': 'N', 'P6': 'N'}, 'locked': [], 'max_parallel': 3, 'throw_s': {'P1': 6, 'P2': 4, 'P4': 6, 'P5': 6, 'P6': 6}, 'default_throw_s': 5}, {'result': 'set', 'starts': {'P4': 0}, 'done_s': 6}), ('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}), ('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 fixture	Actual	Expected	Outcome
regression: undetected point	`{'done_s': 0, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}`	`{'done_s': 5, 'result': 'set', 'starts': {'P1': 0, 'P2': 0}}`	Failed
boundary: locked point already in the right lie	`{'done_s': 0, 'result': 'set', 'starts': {'P2': 0}}`	`{'done_s': 5, 'result': 'set', 'starts': {'P2': 0}}`	Failed
sampled regression 1	`{'done_s': 5, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}`	`{'done_s': 11, 'result': 'set', 'starts': {'P1': 5, 'P3': 0, 'P6': 0}}`	Failed
boundary: locked point needing to move	`{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}`	`{'done_s': 0, 'result': 'blocked:P1', 'starts': {}}`	Passed
regression: three points on two supplies	`{'done_s': 3, 'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}}`	`{'done_s': 8, 'result': 'set', 'starts': {'P1': 0, 'P2': 0, 'P3': 3}}`	Failed
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
control 10	`{'done_s': 0, 'result': 'set', 'starts': {'P4': 0}}`	`{'done_s': 4, 'result': 'set', 'starts': {'P4': 0}}`	Failed

SHA-256 / 6ba061588ce5da422e910d52051525adae396900bfe9c1a3581f684edb259189

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

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 2026-09-29T14:47:51.191730+00:00.

Case digest / 4729e0247ecd4e41ac888bcce5b55984e776b4b99ea9d7c565391cf70ce4d272