FA-67101 / Railway interlocking logic / Open access

Movement authority end computation: margin application · case 01

A length-capped authority is shortened by the safety margin.

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

ROOT CAUSE

The margin is subtracted even from the artificial max-length limit.

VERIFIED REPAIR

Subtract the margin from every hazard end, but not from a max-length cut.

Unsuccessful approach: Subtracting only before occupied sections omits the margin at unlocked sections and route ends.

Case contract

Sections have lengths and states locked, occupied or unlocked; the train front is offset_m into section train_sec (which it occupies itself). Scan the following sections; the end of authority is the start of the first section that is not locked (reason = its state) or the end of the last section (end-of-route). If that exceeds max_ma_m ahead of the train front, the authority is cut to front + max_ma_m (reason max-length). The margin is subtracted from the end except for a max-length cut.

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):
    secs = x['sections']
    bounds = []
    acc = 0
    for s in secs:
        bounds.append(acc)
        acc += s['len']
    k = x['train_sec']
    eoa = acc
    reason = 'end-of-route'
    for j in range(k + 1, len(secs)):
        if secs[j]['state'] != 'locked':
            eoa = bounds[j]
            reason = secs[j]['state']
            break
    front = bounds[k] + x['offset_m']
    if eoa - front > x['max_ma_m']:
        eoa = front + x['max_ma_m']
        reason = 'max-length'
    eoa -= x['margin_m']
    return {'eoa_m': eoa, 'reason': reason}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 24', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 108, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 2308, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('control 1', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 69, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'unlocked'}), ('control 4', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 206, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 1325, 'reason': 'end-of-route'}), ('control 7', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 108, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 550, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('sampled regression 63', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 197, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 497, 'reason': 'max-length'}), ('control 3', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 141, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 450, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('sampled regression 12', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 34, 'max_ma_m': 300, 'margin_m': 50}, {'eoa_m': 884, 'reason': 'max-length'}), ('control 15', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 4, 'offset_m': 137, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 2100, 'reason': 'end-of-route'}), ('control 18', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 3, 'offset_m': 181, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 1250, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: end of route with margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 0, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'end-of-route'}), ('sampled regression 26', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 9, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 409, 'reason': 'max-length'}), ('control 19', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 103, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 925, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('control 23', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 1100, 'reason': 'unlocked'}), ('control 29', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 288, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 1000, 'reason': 'occupied'}), ('control 32', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 344, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 400, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 150, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 30}, {'eoa_m': 220, 'reason': 'unlocked'}), ('sampled regression 75', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 339, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1439, 'reason': 'max-length'}), ('control 41', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 4, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 750, 'reason': 'end-of-route'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('control 34', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 222, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 850, 'reason': 'unlocked'}), ('sampled regression 37', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 2, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 602, 'reason': 'max-length'}), ('control 40', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 25, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 500, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 33', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 33, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 933, 'reason': 'max-length'}), ('control 62', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 203, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 650, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('sampled regression 45', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 348, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1198, 'reason': 'max-length'}), ('control 48', {'sections': [{'len': 500, 'state': 'unlocked'}, {'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 200, 'max_ma_m': 1000, 'margin_m': 25}, {'eoa_m': 1725, 'reason': 'end-of-route'}), ('control 51', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 18, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 1100, 'reason': 'occupied'})]]
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: length cap from the front	`{'eoa_m': 975, 'reason': 'max-length'}`	`{'eoa_m': 1000, 'reason': 'max-length'}`	Failed
boundary: own section occupied	`{'eoa_m': 675, 'reason': 'end-of-route'}`	`{'eoa_m': 675, 'reason': 'end-of-route'}`	Passed
sampled regression 24	`{'eoa_m': 2258, 'reason': 'max-length'}`	`{'eoa_m': 2308, 'reason': 'max-length'}`	Failed
boundary: unlocked section next	`{'eoa_m': 375, 'reason': 'unlocked'}`	`{'eoa_m': 375, 'reason': 'unlocked'}`	Passed
boundary: occupied section two ahead	`{'eoa_m': 375, 'reason': 'occupied'}`	`{'eoa_m': 375, 'reason': 'occupied'}`	Passed
control 1	`{'eoa_m': 150, 'reason': 'unlocked'}`	`{'eoa_m': 150, 'reason': 'unlocked'}`	Passed
control 4	`{'eoa_m': 1325, 'reason': 'end-of-route'}`	`{'eoa_m': 1325, 'reason': 'end-of-route'}`	Passed
control 7	`{'eoa_m': 550, 'reason': 'unlocked'}`	`{'eoa_m': 550, 'reason': 'unlocked'}`	Passed

SHA-256 / be488c702d151de586633ecc1c02c678f8d6ab95f707ec6b7193e2ffa3ac023a

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    secs = x['sections']
    bounds = []
    acc = 0
    for s in secs:
        bounds.append(acc)
        acc += s['len']
    k = x['train_sec']
    eoa = acc
    reason = 'end-of-route'
    for j in range(k + 1, len(secs)):
        if secs[j]['state'] != 'locked':
            eoa = bounds[j]
            reason = secs[j]['state']
            break
    front = bounds[k] + x['offset_m']
    if eoa - front > x['max_ma_m']:
        eoa = front + x['max_ma_m']
        reason = 'max-length'
    if reason == 'occupied':
        eoa -= x['margin_m']
    return {'eoa_m': eoa, 'reason': reason}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 24', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 108, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 2308, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('control 1', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 69, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'unlocked'}), ('control 4', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 206, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 1325, 'reason': 'end-of-route'}), ('control 7', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 108, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 550, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('sampled regression 63', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 197, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 497, 'reason': 'max-length'}), ('control 3', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 141, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 450, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('sampled regression 12', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 34, 'max_ma_m': 300, 'margin_m': 50}, {'eoa_m': 884, 'reason': 'max-length'}), ('control 15', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 4, 'offset_m': 137, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 2100, 'reason': 'end-of-route'}), ('control 18', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 3, 'offset_m': 181, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 1250, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: end of route with margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 0, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'end-of-route'}), ('sampled regression 26', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 9, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 409, 'reason': 'max-length'}), ('control 19', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 103, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 925, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('control 23', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 1100, 'reason': 'unlocked'}), ('control 29', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 288, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 1000, 'reason': 'occupied'}), ('control 32', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 344, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 400, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 150, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 30}, {'eoa_m': 220, 'reason': 'unlocked'}), ('sampled regression 75', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 339, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1439, 'reason': 'max-length'}), ('control 41', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 4, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 750, 'reason': 'end-of-route'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('control 34', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 222, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 850, 'reason': 'unlocked'}), ('sampled regression 37', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 2, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 602, 'reason': 'max-length'}), ('control 40', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 25, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 500, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 33', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 33, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 933, 'reason': 'max-length'}), ('control 62', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 203, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 650, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('sampled regression 45', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 348, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1198, 'reason': 'max-length'}), ('control 48', {'sections': [{'len': 500, 'state': 'unlocked'}, {'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 200, 'max_ma_m': 1000, 'margin_m': 25}, {'eoa_m': 1725, 'reason': 'end-of-route'}), ('control 51', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 18, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 1100, 'reason': 'occupied'})]]
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: length cap from the front	`{'eoa_m': 1000, 'reason': 'max-length'}`	`{'eoa_m': 1000, 'reason': 'max-length'}`	Passed
boundary: own section occupied	`{'eoa_m': 700, 'reason': 'end-of-route'}`	`{'eoa_m': 675, 'reason': 'end-of-route'}`	Failed
sampled regression 24	`{'eoa_m': 2308, 'reason': 'max-length'}`	`{'eoa_m': 2308, 'reason': 'max-length'}`	Passed
boundary: unlocked section next	`{'eoa_m': 400, 'reason': 'unlocked'}`	`{'eoa_m': 375, 'reason': 'unlocked'}`	Failed
boundary: occupied section two ahead	`{'eoa_m': 375, 'reason': 'occupied'}`	`{'eoa_m': 375, 'reason': 'occupied'}`	Passed
control 1	`{'eoa_m': 200, 'reason': 'unlocked'}`	`{'eoa_m': 150, 'reason': 'unlocked'}`	Failed
control 4	`{'eoa_m': 1350, 'reason': 'end-of-route'}`	`{'eoa_m': 1325, 'reason': 'end-of-route'}`	Failed
control 7	`{'eoa_m': 550, 'reason': 'unlocked'}`	`{'eoa_m': 550, 'reason': 'unlocked'}`	Passed

SHA-256 / 0535fe122ee0d2fad5b75d4c45ab478a1c97b210ea54b6e82b5f59c66f28fd37

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    secs = x['sections']
    bounds = []
    acc = 0
    for s in secs:
        bounds.append(acc)
        acc += s['len']
    k = x['train_sec']
    eoa = acc
    reason = 'end-of-route'
    for j in range(k + 1, len(secs)):
        if secs[j]['state'] != 'locked':
            eoa = bounds[j]
            reason = secs[j]['state']
            break
    front = bounds[k] + x['offset_m']
    if eoa - front > x['max_ma_m']:
        eoa = front + x['max_ma_m']
        reason = 'max-length'
    if reason != 'max-length':
        eoa -= x['margin_m']
    return {'eoa_m': eoa, 'reason': reason}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 24', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 108, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 2308, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('control 1', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 69, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'unlocked'}), ('control 4', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 206, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 1325, 'reason': 'end-of-route'}), ('control 7', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 108, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 550, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section next', {'sections': [{'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 300, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 10, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'unlocked'}), ('sampled regression 63', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 197, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 497, 'reason': 'max-length'}), ('control 3', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 141, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 450, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('sampled regression 12', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 34, 'max_ma_m': 300, 'margin_m': 50}, {'eoa_m': 884, 'reason': 'max-length'}), ('control 15', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 4, 'offset_m': 137, 'max_ma_m': 5000, 'margin_m': 0}, {'eoa_m': 2100, 'reason': 'end-of-route'}), ('control 18', {'sections': [{'len': 200, 'state': 'unlocked'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 3, 'offset_m': 181, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 1250, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: end of route with margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 0, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 150, 'reason': 'end-of-route'}), ('sampled regression 26', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 9, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 409, 'reason': 'max-length'}), ('control 19', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 103, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 925, 'reason': 'unlocked'}), ('boundary: cap exactly at the obstacle', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'occupied'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 975, 'reason': 'occupied'}), ('control 23', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 50}, {'eoa_m': 1100, 'reason': 'unlocked'}), ('control 29', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 288, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 1000, 'reason': 'occupied'}), ('control 32', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 344, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 400, 'reason': 'occupied'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: unlocked section margin', {'sections': [{'len': 100, 'state': 'occupied'}, {'len': 150, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 20, 'max_ma_m': 5000, 'margin_m': 30}, {'eoa_m': 220, 'reason': 'unlocked'}), ('sampled regression 75', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}, {'len': 350, 'state': 'unlocked'}, {'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 339, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1439, 'reason': 'max-length'}), ('control 41', {'sections': [{'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 4, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 750, 'reason': 'end-of-route'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('control 34', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}], 'train_sec': 1, 'offset_m': 222, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 850, 'reason': 'unlocked'}), ('sampled regression 37', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 200, 'state': 'unlocked'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 2, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 602, 'reason': 'max-length'}), ('control 40', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 500, 'state': 'unlocked'}, {'len': 100, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 25, 'max_ma_m': 1000, 'margin_m': 0}, {'eoa_m': 500, 'reason': 'unlocked'})], [('regression: length cap from the front', {'sections': [{'len': 500, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 400, 'max_ma_m': 600, 'margin_m': 25}, {'eoa_m': 1000, 'reason': 'max-length'}), ('boundary: own section occupied', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 50, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 675, 'reason': 'end-of-route'}), ('sampled regression 33', {'sections': [{'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 500, 'state': 'locked'}], 'train_sec': 3, 'offset_m': 33, 'max_ma_m': 600, 'margin_m': 50}, {'eoa_m': 933, 'reason': 'max-length'}), ('control 62', {'sections': [{'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 100, 'state': 'unlocked'}], 'train_sec': 0, 'offset_m': 203, 'max_ma_m': 1000, 'margin_m': 50}, {'eoa_m': 650, 'reason': 'unlocked'}), ('boundary: occupied section two ahead', {'sections': [{'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}, {'len': 300, 'state': 'occupied'}, {'len': 100, 'state': 'locked'}], 'train_sec': 0, 'offset_m': 100, 'max_ma_m': 5000, 'margin_m': 25}, {'eoa_m': 375, 'reason': 'occupied'}), ('sampled regression 45', {'sections': [{'len': 350, 'state': 'unlocked'}, {'len': 200, 'state': 'locked'}, {'len': 350, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}, {'len': 200, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 348, 'max_ma_m': 300, 'margin_m': 25}, {'eoa_m': 1198, 'reason': 'max-length'}), ('control 48', {'sections': [{'len': 500, 'state': 'unlocked'}, {'len': 200, 'state': 'unlocked'}, {'len': 350, 'state': 'occupied'}, {'len': 350, 'state': 'locked'}, {'len': 350, 'state': 'locked'}], 'train_sec': 2, 'offset_m': 200, 'max_ma_m': 1000, 'margin_m': 25}, {'eoa_m': 1725, 'reason': 'end-of-route'}), ('control 51', {'sections': [{'len': 500, 'state': 'locked'}, {'len': 100, 'state': 'occupied'}, {'len': 500, 'state': 'locked'}, {'len': 200, 'state': 'occupied'}, {'len': 200, 'state': 'locked'}], 'train_sec': 1, 'offset_m': 18, 'max_ma_m': 600, 'margin_m': 0}, {'eoa_m': 1100, 'reason': 'occupied'})]]
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: length cap from the front	`{'eoa_m': 1000, 'reason': 'max-length'}`	`{'eoa_m': 1000, 'reason': 'max-length'}`	Passed
boundary: own section occupied	`{'eoa_m': 675, 'reason': 'end-of-route'}`	`{'eoa_m': 675, 'reason': 'end-of-route'}`	Passed
sampled regression 24	`{'eoa_m': 2308, 'reason': 'max-length'}`	`{'eoa_m': 2308, 'reason': 'max-length'}`	Passed
boundary: unlocked section next	`{'eoa_m': 375, 'reason': 'unlocked'}`	`{'eoa_m': 375, 'reason': 'unlocked'}`	Passed
boundary: occupied section two ahead	`{'eoa_m': 375, 'reason': 'occupied'}`	`{'eoa_m': 375, 'reason': 'occupied'}`	Passed
control 1	`{'eoa_m': 150, 'reason': 'unlocked'}`	`{'eoa_m': 150, 'reason': 'unlocked'}`	Passed
control 4	`{'eoa_m': 1325, 'reason': 'end-of-route'}`	`{'eoa_m': 1325, 'reason': 'end-of-route'}`	Passed
control 7	`{'eoa_m': 550, 'reason': 'unlocked'}`	`{'eoa_m': 550, 'reason': 'unlocked'}`	Passed

SHA-256 / 7192dd5ec40f35c2fd14053e0509dac1eaba16f9b9c433bd4b3a670677f35bea

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 2026-09-29T14:47:49.821507+00:00.

Case digest / 851780e61737c77790d641b86e00dffed38caa773c3380fc764e68cb8212620f