FA-67761 / Elevator dispatch scheduling / Open access

Single car SCAN service simulation: alight before boarding · case 01

Waiting passengers are left behind at a floor where riders are getting out.

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ROOT CAUSE

Boarding is evaluated before the riders at this floor have alighted, so the car still looks full.

VERIFIED REPAIR

Let riders alight first and then board against the reduced load.

Unsuccessful approach: Snapshotting the load before alighting still counts the departing riders against capacity.

Case contract

All passengers [id, from, to] wait at time 0. The car starts at start heading up. At each floor it first lets riders alight, then boards waiting passengers (in id order) whose travel direction equals the car direction while load < cap; any alighting or boarding costs one stop_s. If no rider destination or waiting origin lies strictly ahead it reverses in place (and may board again); otherwise it moves one floor (floor_s). Return {id: [board time, alight time]} for delivered passengers.

Why this case matters

Lift group controllers make these decisions many times per minute; a wrong answer strands passengers, wastes trips or overrides a safety rule.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(x):
    cap = x['cap']
    pos = x['start']
    t = 0
    d = 'up'
    waiting = {r[0]: r for r in x['requests']}
    riding = {}
    picked = {}
    done = {}
    for _ in range(400):
        if not waiting and not riding:
            break
        stopped = False
        for pid in sorted(waiting):
            r = waiting[pid]
            rdir = 'up' if r[2] > r[1] else 'down'
            if r[1] == pos and rdir == d and len(riding) < cap:
                riding[pid] = r
                picked[pid] = t
                del waiting[pid]
                stopped = True
        for pid in sorted(riding):
            if riding[pid][2] == pos:
                done[pid] = [picked[pid], t]
                del riding[pid]
                stopped = True
        if stopped:
            t += x['stop_s']
        targets = [r[2] for r in riding.values()] + [r[1] for r in waiting.values()]
        ahead = [f for f in targets if (f > pos if d == 'up' else f < pos)]
        if not ahead:
            d = 'down' if d == 'up' else 'up'
            continue
        pos += 1 if d == 'up' else -1
        t += x['floor_s']
    return done
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 1', {'cap': 1, 'start': 5, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 6, 8], ['p1', 3, 7], ['p2', 0, 7], ['p3', 3, 2], ['p4', 7, 1]]}, {'p0': [2, 11], 'p4': [18, 35], 'p2': [42, 61], 'p3': [74, 81], 'p1': [88, 101]}), ('control 4', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 8], ['p1', 8, 1], ['p2', 0, 8], ['p3', 5, 6]]}, {'p3': [13, 20], 'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81]}), ('control 7', {'cap': 4, 'start': 6, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 7, 5], ['p2', 6, 0]]}, {'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 28', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 2, 5], ['p1', 0, 5], ['p2', 7, 1], ['p3', 5, 3], ['p4', 5, 0]]}, {'p3': [14, 26], 'p2': [2, 38], 'p0': [60, 74], 'p1': [48, 74], 'p4': [82, 100]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 12', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 3], ['p1', 8, 4], ['p2', 2, 8], ['p3', 5, 0], ['p4', 8, 2], ['p5', 7, 9]]}, {'p2': [0, 28], 'p5': [18, 38], 'p1': [48, 72], 'p0': [48, 82], 'p4': [48, 92], 'p3': [62, 104]}), ('control 15', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 6, 3], ['p1', 4, 1], ['p2', 5, 0]]}, {'p0': [4, 26], 'p2': [14, 40], 'p1': [56, 70]}), ('control 18', {'cap': 4, 'start': 9, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 1, 0], ['p1', 7, 8], ['p2', 1, 8]]}, {'p0': [16, 26], 'p1': [56, 66], 'p2': [36, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('sampled regression 69', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 3, 9], ['p1', 8, 1], ['p2', 4, 8], ['p3', 4, 7], ['p4', 7, 8]]}, {'p3': [0, 14], 'p2': [0, 24], 'p4': [14, 24], 'p1': [32, 54], 'p0': [66, 86]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 23', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 9, 4], ['p1', 9, 1], ['p2', 0, 1], ['p3', 6, 2]]}, {'p0': [2, 22], 'p3': [13, 31], 'p1': [2, 38], 'p2': [45, 52]}), ('control 26', {'cap': 1, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 0, 4], ['p1', 1, 6], ['p2', 1, 6], ['p3', 5, 1]]}, {'p3': [4, 20], 'p0': [30, 46], 'p1': [60, 78], 'p2': [96, 114]}), ('control 29', {'cap': 4, 'start': 5, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 5], ['p1', 0, 2], ['p2', 7, 1]]}, {'p0': [6, 28], 'p2': [16, 44], 'p1': [54, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 8', {'cap': 1, 'start': 7, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 4, 9], ['p1', 9, 3], ['p2', 9, 7], ['p3', 2, 1], ['p4', 1, 3]]}, {'p1': [4, 24], 'p3': [34, 44], 'p4': [52, 64], 'p0': [74, 92], 'p2': [100, 112]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 34', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 2, 8], ['p2', 6, 1], ['p3', 3, 7], ['p4', 6, 8], ['p5', 2, 4]]}, {'p4': [4, 13], 'p2': [22, 42], 'p0': [35, 49], 'p5': [58, 67], 'p1': [58, 80], 'p3': [95, 108]}), ('control 37', {'cap': 2, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 5, 9], ['p1', 6, 7]]}, {'p1': [13, 20], 'p0': [6, 29]}), ('control 43', {'cap': 4, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 7, 4], ['p1', 2, 1], ['p2', 7, 5], ['p3', 5, 1]]}, {'p2': [8, 20], 'p0': [8, 30], 'p1': [42, 52], 'p3': [20, 52]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 45', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 0, 2], ['p1', 6, 2], ['p2', 4, 5], ['p3', 1, 7], ['p4', 7, 4]]}, {'p4': [2, 18], 'p1': [9, 27], 'p0': [36, 50], 'p2': [59, 66], 'p3': [43, 75]}), ('control 48', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 0, 2], ['p2', 8, 5], ['p3', 6, 4], ['p4', 0, 3]]}, {'p2': [0, 16], 'p3': [9, 23], 'p0': [32, 41], 'p1': [46, 55], 'p4': [46, 62]}), ('control 51', {'cap': 4, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 2, 6], ['p2', 8, 1], ['p3', 1, 6], ['p4', 3, 1]]}, {'p0': [8, 15], 'p2': [22, 46], 'p4': [37, 46], 'p1': [58, 71], 'p3': [51, 71]})]]
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: full car at a floor where a rider alights	`{'a': [0, 11], 'b': [16, 27]}`	`{'a': [0, 11], 'b': [11, 22]}`	Failed
sampled regression 40	`{'p0': [6, 30], 'p1': [16, 42], 'p2': [54, 64]}`	`{'p0': [6, 30], 'p1': [16, 50], 'p2': [30, 40]}`	Failed
boundary: capacity exactly reached	`{'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}`	`{'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}`	Passed
boundary: opposite-direction passenger waits	`{'a': [22, 31], 'b': [0, 11]}`	`{'a': [22, 31], 'b': [0, 11]}`	Passed
boundary: two boardings share one stop	`{'a': [0, 14], 'b': [0, 14]}`	`{'a': [0, 14], 'b': [0, 14]}`	Passed
control 1	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	Passed
control 4	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	Passed
control 7	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	Passed

SHA-256 / 76145449cf7a1921cf7b826510ba76013d8922a5326e33001749314c1b9d30e1

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    cap = x['cap']
    pos = x['start']
    t = 0
    d = 'up'
    waiting = {r[0]: r for r in x['requests']}
    riding = {}
    picked = {}
    done = {}
    for _ in range(400):
        if not waiting and not riding:
            break
        stopped = False
        load_before = len(riding)
        for pid in sorted(riding):
            if riding[pid][2] == pos:
                done[pid] = [picked[pid], t]
                del riding[pid]
                stopped = True
        for pid in sorted(waiting):
            r = waiting[pid]
            rdir = 'up' if r[2] > r[1] else 'down'
            if r[1] == pos and rdir == d and load_before < cap:
                riding[pid] = r
                picked[pid] = t
                del waiting[pid]
                stopped = True
        if stopped:
            t += x['stop_s']
        targets = [r[2] for r in riding.values()] + [r[1] for r in waiting.values()]
        ahead = [f for f in targets if (f > pos if d == 'up' else f < pos)]
        if not ahead:
            d = 'down' if d == 'up' else 'up'
            continue
        pos += 1 if d == 'up' else -1
        t += x['floor_s']
    return done
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 1', {'cap': 1, 'start': 5, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 6, 8], ['p1', 3, 7], ['p2', 0, 7], ['p3', 3, 2], ['p4', 7, 1]]}, {'p0': [2, 11], 'p4': [18, 35], 'p2': [42, 61], 'p3': [74, 81], 'p1': [88, 101]}), ('control 4', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 8], ['p1', 8, 1], ['p2', 0, 8], ['p3', 5, 6]]}, {'p3': [13, 20], 'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81]}), ('control 7', {'cap': 4, 'start': 6, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 7, 5], ['p2', 6, 0]]}, {'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 28', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 2, 5], ['p1', 0, 5], ['p2', 7, 1], ['p3', 5, 3], ['p4', 5, 0]]}, {'p3': [14, 26], 'p2': [2, 38], 'p0': [60, 74], 'p1': [48, 74], 'p4': [82, 100]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 12', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 3], ['p1', 8, 4], ['p2', 2, 8], ['p3', 5, 0], ['p4', 8, 2], ['p5', 7, 9]]}, {'p2': [0, 28], 'p5': [18, 38], 'p1': [48, 72], 'p0': [48, 82], 'p4': [48, 92], 'p3': [62, 104]}), ('control 15', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 6, 3], ['p1', 4, 1], ['p2', 5, 0]]}, {'p0': [4, 26], 'p2': [14, 40], 'p1': [56, 70]}), ('control 18', {'cap': 4, 'start': 9, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 1, 0], ['p1', 7, 8], ['p2', 1, 8]]}, {'p0': [16, 26], 'p1': [56, 66], 'p2': [36, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('sampled regression 69', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 3, 9], ['p1', 8, 1], ['p2', 4, 8], ['p3', 4, 7], ['p4', 7, 8]]}, {'p3': [0, 14], 'p2': [0, 24], 'p4': [14, 24], 'p1': [32, 54], 'p0': [66, 86]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 23', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 9, 4], ['p1', 9, 1], ['p2', 0, 1], ['p3', 6, 2]]}, {'p0': [2, 22], 'p3': [13, 31], 'p1': [2, 38], 'p2': [45, 52]}), ('control 26', {'cap': 1, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 0, 4], ['p1', 1, 6], ['p2', 1, 6], ['p3', 5, 1]]}, {'p3': [4, 20], 'p0': [30, 46], 'p1': [60, 78], 'p2': [96, 114]}), ('control 29', {'cap': 4, 'start': 5, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 5], ['p1', 0, 2], ['p2', 7, 1]]}, {'p0': [6, 28], 'p2': [16, 44], 'p1': [54, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 8', {'cap': 1, 'start': 7, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 4, 9], ['p1', 9, 3], ['p2', 9, 7], ['p3', 2, 1], ['p4', 1, 3]]}, {'p1': [4, 24], 'p3': [34, 44], 'p4': [52, 64], 'p0': [74, 92], 'p2': [100, 112]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 34', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 2, 8], ['p2', 6, 1], ['p3', 3, 7], ['p4', 6, 8], ['p5', 2, 4]]}, {'p4': [4, 13], 'p2': [22, 42], 'p0': [35, 49], 'p5': [58, 67], 'p1': [58, 80], 'p3': [95, 108]}), ('control 37', {'cap': 2, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 5, 9], ['p1', 6, 7]]}, {'p1': [13, 20], 'p0': [6, 29]}), ('control 43', {'cap': 4, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 7, 4], ['p1', 2, 1], ['p2', 7, 5], ['p3', 5, 1]]}, {'p2': [8, 20], 'p0': [8, 30], 'p1': [42, 52], 'p3': [20, 52]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 45', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 0, 2], ['p1', 6, 2], ['p2', 4, 5], ['p3', 1, 7], ['p4', 7, 4]]}, {'p4': [2, 18], 'p1': [9, 27], 'p0': [36, 50], 'p2': [59, 66], 'p3': [43, 75]}), ('control 48', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 0, 2], ['p2', 8, 5], ['p3', 6, 4], ['p4', 0, 3]]}, {'p2': [0, 16], 'p3': [9, 23], 'p0': [32, 41], 'p1': [46, 55], 'p4': [46, 62]}), ('control 51', {'cap': 4, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 2, 6], ['p2', 8, 1], ['p3', 1, 6], ['p4', 3, 1]]}, {'p0': [8, 15], 'p2': [22, 46], 'p4': [37, 46], 'p1': [58, 71], 'p3': [51, 71]})]]
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: full car at a floor where a rider alights	`{'a': [0, 11], 'b': [16, 27]}`	`{'a': [0, 11], 'b': [11, 22]}`	Failed
sampled regression 40	`{'p0': [6, 30], 'p1': [16, 42], 'p2': [54, 64]}`	`{'p0': [6, 30], 'p1': [16, 50], 'p2': [30, 40]}`	Failed
boundary: capacity exactly reached	`{'a': [0, 13], 'b': [0, 20], 'c': [0, 27]}`	`{'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}`	Failed
boundary: opposite-direction passenger waits	`{'a': [22, 31], 'b': [0, 11]}`	`{'a': [22, 31], 'b': [0, 11]}`	Passed
boundary: two boardings share one stop	`{'a': [0, 14], 'b': [0, 14]}`	`{'a': [0, 14], 'b': [0, 14]}`	Passed
control 1	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	Passed
control 4	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	Passed
control 7	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	Passed

SHA-256 / 081d32eb8c8cd0d4deed7a318263aed7876b01f57263738a1d770cfac33a651f

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    cap = x['cap']
    pos = x['start']
    t = 0
    d = 'up'
    waiting = {r[0]: r for r in x['requests']}
    riding = {}
    picked = {}
    done = {}
    for _ in range(400):
        if not waiting and not riding:
            break
        stopped = False
        for pid in sorted(riding):
            if riding[pid][2] == pos:
                done[pid] = [picked[pid], t]
                del riding[pid]
                stopped = True
        for pid in sorted(waiting):
            r = waiting[pid]
            rdir = 'up' if r[2] > r[1] else 'down'
            if r[1] == pos and rdir == d and len(riding) < cap:
                riding[pid] = r
                picked[pid] = t
                del waiting[pid]
                stopped = True
        if stopped:
            t += x['stop_s']
        targets = [r[2] for r in riding.values()] + [r[1] for r in waiting.values()]
        ahead = [f for f in targets if (f > pos if d == 'up' else f < pos)]
        if not ahead:
            d = 'down' if d == 'up' else 'up'
            continue
        pos += 1 if d == 'up' else -1
        t += x['floor_s']
    return done
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 1', {'cap': 1, 'start': 5, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 6, 8], ['p1', 3, 7], ['p2', 0, 7], ['p3', 3, 2], ['p4', 7, 1]]}, {'p0': [2, 11], 'p4': [18, 35], 'p2': [42, 61], 'p3': [74, 81], 'p1': [88, 101]}), ('control 4', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 8], ['p1', 8, 1], ['p2', 0, 8], ['p3', 5, 6]]}, {'p3': [13, 20], 'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81]}), ('control 7', {'cap': 4, 'start': 6, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 7, 5], ['p2', 6, 0]]}, {'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 28', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 2, 5], ['p1', 0, 5], ['p2', 7, 1], ['p3', 5, 3], ['p4', 5, 0]]}, {'p3': [14, 26], 'p2': [2, 38], 'p0': [60, 74], 'p1': [48, 74], 'p4': [82, 100]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('control 12', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 3], ['p1', 8, 4], ['p2', 2, 8], ['p3', 5, 0], ['p4', 8, 2], ['p5', 7, 9]]}, {'p2': [0, 28], 'p5': [18, 38], 'p1': [48, 72], 'p0': [48, 82], 'p4': [48, 92], 'p3': [62, 104]}), ('control 15', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 6, 3], ['p1', 4, 1], ['p2', 5, 0]]}, {'p0': [4, 26], 'p2': [14, 40], 'p1': [56, 70]}), ('control 18', {'cap': 4, 'start': 9, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 1, 0], ['p1', 7, 8], ['p2', 1, 8]]}, {'p0': [16, 26], 'p1': [56, 66], 'p2': [36, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('sampled regression 69', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 3, 9], ['p1', 8, 1], ['p2', 4, 8], ['p3', 4, 7], ['p4', 7, 8]]}, {'p3': [0, 14], 'p2': [0, 24], 'p4': [14, 24], 'p1': [32, 54], 'p0': [66, 86]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 23', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 9, 4], ['p1', 9, 1], ['p2', 0, 1], ['p3', 6, 2]]}, {'p0': [2, 22], 'p3': [13, 31], 'p1': [2, 38], 'p2': [45, 52]}), ('control 26', {'cap': 1, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 0, 4], ['p1', 1, 6], ['p2', 1, 6], ['p3', 5, 1]]}, {'p3': [4, 20], 'p0': [30, 46], 'p1': [60, 78], 'p2': [96, 114]}), ('control 29', {'cap': 4, 'start': 5, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 8, 5], ['p1', 0, 2], ['p2', 7, 1]]}, {'p0': [6, 28], 'p2': [16, 44], 'p1': [54, 66]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('boundary: capacity exactly reached', {'cap': 2, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 4], ['b', 0, 5], ['c', 0, 6]]}, {'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('control 8', {'cap': 1, 'start': 7, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 4, 9], ['p1', 9, 3], ['p2', 9, 7], ['p3', 2, 1], ['p4', 1, 3]]}, {'p1': [4, 24], 'p3': [34, 44], 'p4': [52, 64], 'p0': [74, 92], 'p2': [100, 112]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 34', {'cap': 2, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 2, 8], ['p2', 6, 1], ['p3', 3, 7], ['p4', 6, 8], ['p5', 2, 4]]}, {'p4': [4, 13], 'p2': [22, 42], 'p0': [35, 49], 'p5': [58, 67], 'p1': [58, 80], 'p3': [95, 108]}), ('control 37', {'cap': 2, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 5, 9], ['p1', 6, 7]]}, {'p1': [13, 20], 'p0': [6, 29]}), ('control 43', {'cap': 4, 'start': 3, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 7, 4], ['p1', 2, 1], ['p2', 7, 5], ['p3', 5, 1]]}, {'p2': [8, 20], 'p0': [8, 30], 'p1': [42, 52], 'p3': [20, 52]})], [('regression: full car at a floor where a rider alights', {'cap': 1, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 3], ['b', 3, 6]]}, {'a': [0, 11], 'b': [11, 22]}), ('sampled regression 40', {'cap': 2, 'start': 6, 'floor_s': 2, 'stop_s': 8, 'requests': [['p0', 9, 5], ['p1', 8, 3], ['p2', 5, 4]]}, {'p0': [6, 30], 'p2': [30, 40], 'p1': [16, 50]}), ('boundary: two boardings share one stop', {'cap': 4, 'start': 1, 'floor_s': 2, 'stop_s': 8, 'requests': [['a', 1, 4], ['b', 1, 4]]}, {'a': [0, 14], 'b': [0, 14]}), ('boundary: alighting-only stop', {'cap': 4, 'start': 0, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 0, 2], ['b', 5, 6]]}, {'a': [0, 9], 'b': [20, 27]}), ('boundary: opposite-direction passenger waits', {'cap': 4, 'start': 2, 'floor_s': 2, 'stop_s': 5, 'requests': [['a', 2, 0], ['b', 2, 5]]}, {'b': [0, 11], 'a': [22, 31]}), ('control 45', {'cap': 4, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 0, 2], ['p1', 6, 2], ['p2', 4, 5], ['p3', 1, 7], ['p4', 7, 4]]}, {'p4': [2, 18], 'p1': [9, 27], 'p0': [36, 50], 'p2': [59, 66], 'p3': [43, 75]}), ('control 48', {'cap': 2, 'start': 8, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 2, 0], ['p1', 0, 2], ['p2', 8, 5], ['p3', 6, 4], ['p4', 0, 3]]}, {'p2': [0, 16], 'p3': [9, 23], 'p0': [32, 41], 'p1': [46, 55], 'p4': [46, 62]}), ('control 51', {'cap': 4, 'start': 4, 'floor_s': 2, 'stop_s': 5, 'requests': [['p0', 8, 9], ['p1', 2, 6], ['p2', 8, 1], ['p3', 1, 6], ['p4', 3, 1]]}, {'p0': [8, 15], 'p2': [22, 46], 'p4': [37, 46], 'p1': [58, 71], 'p3': [51, 71]})]]
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: full car at a floor where a rider alights	`{'a': [0, 11], 'b': [11, 22]}`	`{'a': [0, 11], 'b': [11, 22]}`	Passed
sampled regression 40	`{'p0': [6, 30], 'p1': [16, 50], 'p2': [30, 40]}`	`{'p0': [6, 30], 'p1': [16, 50], 'p2': [30, 40]}`	Passed
boundary: capacity exactly reached	`{'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}`	`{'a': [0, 13], 'b': [0, 20], 'c': [35, 52]}`	Passed
boundary: opposite-direction passenger waits	`{'a': [22, 31], 'b': [0, 11]}`	`{'a': [22, 31], 'b': [0, 11]}`	Passed
boundary: two boardings share one stop	`{'a': [0, 14], 'b': [0, 14]}`	`{'a': [0, 14], 'b': [0, 14]}`	Passed
control 1	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	`{'p0': [2, 11], 'p1': [88, 101], 'p2': [42, 61], 'p3': [74, 81], 'p4': [18, 35]}`	Passed
control 4	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	`{'p0': [2, 29], 'p1': [34, 53], 'p2': [60, 81], 'p3': [13, 20]}`	Passed
control 7	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	`{'p0': [4, 11], 'p1': [20, 34], 'p2': [27, 49]}`	Passed

SHA-256 / 6b4a094efafd8de335822481ba8da4ae1f7bc3823b337c52a167a1fc778abd7a

Verification & scope

Stipulated toy lift-control contract for a bounded teaching model; it makes no claim of conformance to any lift code or vendor dispatcher 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 2026-09-29T14:47:55.913272+00:00.

Case digest / 67e159b414f7fde97a7fcdf70e7160ae54cfe8a9eebc982e591d932be4b37632