FA-67551 / Elevator dispatch scheduling / Open access

Hall call ETA with intermediate stops: reversal path length · case 01

The ETA forgets the distance run beyond the car position before reversing.

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

ROOT CAUSE

The return leg is measured from the current floor instead of from the reversal floor.

VERIFIED REPAIR

Travel to the reversal floor and back down to the target.

Unsuccessful approach: Using the straight distance ignores the reversal completely.

Case contract

A moving car at floor with direction and car stops estimates its arrival at a hall call (target, call direction). Work in the car direction (mirror floors for down). If the target is strictly ahead and the call is in the car direction, the car goes straight there, stopping at stops strictly between. Otherwise it runs to the farthest of its stops ahead and the target, reverses and returns to the target, stopping at every stop ahead plus stops strictly between target and floor behind. A stop at the target floor is not extra. ETA = floors travelled * per_floor_s + stops * stop_s.

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):
    sg = 1 if x['dir'] == 'up' else -1
    f = x['floor'] * sg
    t = x['target'] * sg
    stops = [s * sg for s in x['stops'] if s * sg != t]
    same = x['call_dir'] == x['dir']
    if t > f and same:
        path = t - f
        n = len([s for s in stops if f < s < t])
    else:
        ahead = [s for s in stops if s > f]
        far = max(ahead + [t, f])
        path = (far - f) + abs(f - t)
        n = len(ahead) + len([s for s in stops if t < s < f])
    return path * x['per_floor_s'] + n * x['stop_s']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 1', {'floor': 6, 'dir': 'down', 'target': 12, 'call_dir': 'down', 'stops': [3, 4], 'per_floor_s': 2, 'stop_s': 12}, 48), ('control 4', {'floor': 1, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [3, 10, 5], 'per_floor_s': 2, 'stop_s': 12}, 62), ('control 7', {'floor': 7, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [1, 13, 9, 2], 'per_floor_s': 3, 'stop_s': 12}, 24)], [('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('sampled regression 13', {'floor': 2, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [4], 'per_floor_s': 3, 'stop_s': 12}, 24), ('sampled regression 3', {'floor': 13, 'dir': 'up', 'target': 9, 'call_dir': 'up', 'stops': [2, 15, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 32), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('control 12', {'floor': 12, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 8, 7, 15], 'per_floor_s': 3, 'stop_s': 10}, 3), ('control 15', {'floor': 15, 'dir': 'up', 'target': 11, 'call_dir': 'down', 'stops': [3], 'per_floor_s': 3, 'stop_s': 12}, 12), ('control 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16)], [('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59), ('sampled regression 33', {'floor': 5, 'dir': 'up', 'target': 0, 'call_dir': 'down', 'stops': [6, 0, 15], 'per_floor_s': 3, 'stop_s': 10}, 95), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: stop at the target floor', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'up', 'stops': [8, 5], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 23', {'floor': 4, 'dir': 'up', 'target': 13, 'call_dir': 'up', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 18), ('sampled regression 26', {'floor': 14, 'dir': 'up', 'target': 15, 'call_dir': 'down', 'stops': [1, 14], 'per_floor_s': 2, 'stop_s': 8}, 2), ('control 29', {'floor': 8, 'dir': 'down', 'target': 6, 'call_dir': 'down', 'stops': [14, 15, 3], 'per_floor_s': 3, 'stop_s': 10}, 6)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 53', {'floor': 0, 'dir': 'up', 'target': 5, 'call_dir': 'down', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 10), ('sampled regression 61', {'floor': 11, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [9, 11, 6, 8], 'per_floor_s': 2, 'stop_s': 8}, 50), ('boundary: stops beyond the target', {'floor': 2, 'dir': 'up', 'target': 6, 'call_dir': 'up', 'stops': [4, 10], 'per_floor_s': 2, 'stop_s': 10}, 18), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 34', {'floor': 7, 'dir': 'down', 'target': 7, 'call_dir': 'up', 'stops': [10, 7], 'per_floor_s': 2, 'stop_s': 8}, 0), ('control 37', {'floor': 14, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [7, 4, 13, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59)], [('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 71', {'floor': 13, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [6, 14, 15, 11], 'per_floor_s': 3, 'stop_s': 10}, 76), ('sampled regression 77', {'floor': 12, 'dir': 'down', 'target': 8, 'call_dir': 'up', 'stops': [14, 10, 3], 'per_floor_s': 3, 'stop_s': 12}, 66), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('control 45', {'floor': 2, 'dir': 'down', 'target': 0, 'call_dir': 'down', 'stops': [3, 12, 7, 11], 'per_floor_s': 2, 'stop_s': 8}, 4), ('sampled regression 48', {'floor': 8, 'dir': 'down', 'target': 2, 'call_dir': 'up', 'stops': [8, 7, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 42), ('control 51', {'floor': 11, 'dir': 'up', 'target': 4, 'call_dir': 'down', 'stops': [], 'per_floor_s': 3, 'stop_s': 12}, 21)]]
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: call behind a down car	`22`	`30`	Failed
regression: stops behind served on return	`36`	`42`	Failed
regression: call ahead but opposite direction	`50`	`44`	Failed
boundary: down car mirrored	`22`	`22`	Passed
regression: call at the current floor	`18`	`26`	Failed
sampled regression 1	`42`	`48`	Failed
control 4	`62`	`62`	Passed
control 7	`24`	`24`	Passed

SHA-256 / ac65a55cb638984016bae4723e9376933108c745ecd01bbfd0d9d70b4c5babd5

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    sg = 1 if x['dir'] == 'up' else -1
    f = x['floor'] * sg
    t = x['target'] * sg
    stops = [s * sg for s in x['stops'] if s * sg != t]
    same = x['call_dir'] == x['dir']
    if t > f and same:
        path = t - f
        n = len([s for s in stops if f < s < t])
    else:
        ahead = [s for s in stops if s > f]
        far = max(ahead + [t, f])
        path = abs(t - f)
        n = len(ahead) + len([s for s in stops if t < s < f])
    return path * x['per_floor_s'] + n * x['stop_s']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 1', {'floor': 6, 'dir': 'down', 'target': 12, 'call_dir': 'down', 'stops': [3, 4], 'per_floor_s': 2, 'stop_s': 12}, 48), ('control 4', {'floor': 1, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [3, 10, 5], 'per_floor_s': 2, 'stop_s': 12}, 62), ('control 7', {'floor': 7, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [1, 13, 9, 2], 'per_floor_s': 3, 'stop_s': 12}, 24)], [('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('sampled regression 13', {'floor': 2, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [4], 'per_floor_s': 3, 'stop_s': 12}, 24), ('sampled regression 3', {'floor': 13, 'dir': 'up', 'target': 9, 'call_dir': 'up', 'stops': [2, 15, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 32), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('control 12', {'floor': 12, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 8, 7, 15], 'per_floor_s': 3, 'stop_s': 10}, 3), ('control 15', {'floor': 15, 'dir': 'up', 'target': 11, 'call_dir': 'down', 'stops': [3], 'per_floor_s': 3, 'stop_s': 12}, 12), ('control 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16)], [('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59), ('sampled regression 33', {'floor': 5, 'dir': 'up', 'target': 0, 'call_dir': 'down', 'stops': [6, 0, 15], 'per_floor_s': 3, 'stop_s': 10}, 95), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: stop at the target floor', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'up', 'stops': [8, 5], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 23', {'floor': 4, 'dir': 'up', 'target': 13, 'call_dir': 'up', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 18), ('sampled regression 26', {'floor': 14, 'dir': 'up', 'target': 15, 'call_dir': 'down', 'stops': [1, 14], 'per_floor_s': 2, 'stop_s': 8}, 2), ('control 29', {'floor': 8, 'dir': 'down', 'target': 6, 'call_dir': 'down', 'stops': [14, 15, 3], 'per_floor_s': 3, 'stop_s': 10}, 6)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 53', {'floor': 0, 'dir': 'up', 'target': 5, 'call_dir': 'down', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 10), ('sampled regression 61', {'floor': 11, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [9, 11, 6, 8], 'per_floor_s': 2, 'stop_s': 8}, 50), ('boundary: stops beyond the target', {'floor': 2, 'dir': 'up', 'target': 6, 'call_dir': 'up', 'stops': [4, 10], 'per_floor_s': 2, 'stop_s': 10}, 18), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 34', {'floor': 7, 'dir': 'down', 'target': 7, 'call_dir': 'up', 'stops': [10, 7], 'per_floor_s': 2, 'stop_s': 8}, 0), ('control 37', {'floor': 14, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [7, 4, 13, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59)], [('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 71', {'floor': 13, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [6, 14, 15, 11], 'per_floor_s': 3, 'stop_s': 10}, 76), ('sampled regression 77', {'floor': 12, 'dir': 'down', 'target': 8, 'call_dir': 'up', 'stops': [14, 10, 3], 'per_floor_s': 3, 'stop_s': 12}, 66), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('control 45', {'floor': 2, 'dir': 'down', 'target': 0, 'call_dir': 'down', 'stops': [3, 12, 7, 11], 'per_floor_s': 2, 'stop_s': 8}, 4), ('sampled regression 48', {'floor': 8, 'dir': 'down', 'target': 2, 'call_dir': 'up', 'stops': [8, 7, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 42), ('control 51', {'floor': 11, 'dir': 'up', 'target': 4, 'call_dir': 'down', 'stops': [], 'per_floor_s': 3, 'stop_s': 12}, 21)]]
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: call behind a down car	`14`	`30`	Failed
regression: stops behind served on return	`30`	`42`	Failed
regression: call ahead but opposite direction	`32`	`44`	Failed
boundary: down car mirrored	`22`	`22`	Passed
regression: call at the current floor	`10`	`26`	Failed
sampled regression 1	`36`	`48`	Failed
control 4	`62`	`62`	Passed
control 7	`24`	`24`	Passed

SHA-256 / 0621f924711cd4e53acb331b37bd93de1077f2c015edf4c1ad07be0a91acb1a2

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    sg = 1 if x['dir'] == 'up' else -1
    f = x['floor'] * sg
    t = x['target'] * sg
    stops = [s * sg for s in x['stops'] if s * sg != t]
    same = x['call_dir'] == x['dir']
    if t > f and same:
        path = t - f
        n = len([s for s in stops if f < s < t])
    else:
        ahead = [s for s in stops if s > f]
        far = max(ahead + [t, f])
        path = (far - f) + (far - t)
        n = len(ahead) + len([s for s in stops if t < s < f])
    return path * x['per_floor_s'] + n * x['stop_s']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 1', {'floor': 6, 'dir': 'down', 'target': 12, 'call_dir': 'down', 'stops': [3, 4], 'per_floor_s': 2, 'stop_s': 12}, 48), ('control 4', {'floor': 1, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [3, 10, 5], 'per_floor_s': 2, 'stop_s': 12}, 62), ('control 7', {'floor': 7, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [1, 13, 9, 2], 'per_floor_s': 3, 'stop_s': 12}, 24)], [('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('sampled regression 13', {'floor': 2, 'dir': 'up', 'target': 2, 'call_dir': 'down', 'stops': [4], 'per_floor_s': 3, 'stop_s': 12}, 24), ('sampled regression 3', {'floor': 13, 'dir': 'up', 'target': 9, 'call_dir': 'up', 'stops': [2, 15, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 32), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('control 12', {'floor': 12, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 8, 7, 15], 'per_floor_s': 3, 'stop_s': 10}, 3), ('control 15', {'floor': 15, 'dir': 'up', 'target': 11, 'call_dir': 'down', 'stops': [3], 'per_floor_s': 3, 'stop_s': 12}, 12), ('control 18', {'floor': 1, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [8, 2, 11, 1], 'per_floor_s': 2, 'stop_s': 10}, 16)], [('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59), ('sampled regression 33', {'floor': 5, 'dir': 'up', 'target': 0, 'call_dir': 'down', 'stops': [6, 0, 15], 'per_floor_s': 3, 'stop_s': 10}, 95), ('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('boundary: stop at the target floor', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'up', 'stops': [8, 5], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 23', {'floor': 4, 'dir': 'up', 'target': 13, 'call_dir': 'up', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 18), ('sampled regression 26', {'floor': 14, 'dir': 'up', 'target': 15, 'call_dir': 'down', 'stops': [1, 14], 'per_floor_s': 2, 'stop_s': 8}, 2), ('control 29', {'floor': 8, 'dir': 'down', 'target': 6, 'call_dir': 'down', 'stops': [14, 15, 3], 'per_floor_s': 3, 'stop_s': 10}, 6)], [('regression: stops behind served on return', {'floor': 6, 'dir': 'up', 'target': 1, 'call_dir': 'up', 'stops': [9, 3], 'per_floor_s': 2, 'stop_s': 10}, 42), ('sampled regression 53', {'floor': 0, 'dir': 'up', 'target': 5, 'call_dir': 'down', 'stops': [], 'per_floor_s': 2, 'stop_s': 12}, 10), ('sampled regression 61', {'floor': 11, 'dir': 'down', 'target': 14, 'call_dir': 'down', 'stops': [9, 11, 6, 8], 'per_floor_s': 2, 'stop_s': 8}, 50), ('boundary: stops beyond the target', {'floor': 2, 'dir': 'up', 'target': 6, 'call_dir': 'up', 'stops': [4, 10], 'per_floor_s': 2, 'stop_s': 10}, 18), ('boundary: down car mirrored', {'floor': 10, 'dir': 'down', 'target': 4, 'call_dir': 'down', 'stops': [7], 'per_floor_s': 2, 'stop_s': 10}, 22), ('control 34', {'floor': 7, 'dir': 'down', 'target': 7, 'call_dir': 'up', 'stops': [10, 7], 'per_floor_s': 2, 'stop_s': 8}, 0), ('control 37', {'floor': 14, 'dir': 'up', 'target': 11, 'call_dir': 'up', 'stops': [7, 4, 13, 1], 'per_floor_s': 2, 'stop_s': 10}, 16), ('sampled regression 40', {'floor': 10, 'dir': 'down', 'target': 11, 'call_dir': 'down', 'stops': [4, 10, 12, 5], 'per_floor_s': 3, 'stop_s': 10}, 59)], [('regression: call behind a down car', {'floor': 10, 'dir': 'down', 'target': 12, 'call_dir': 'up', 'stops': [6], 'per_floor_s': 2, 'stop_s': 10}, 30), ('sampled regression 71', {'floor': 13, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [6, 14, 15, 11], 'per_floor_s': 3, 'stop_s': 10}, 76), ('sampled regression 77', {'floor': 12, 'dir': 'down', 'target': 8, 'call_dir': 'up', 'stops': [14, 10, 3], 'per_floor_s': 3, 'stop_s': 12}, 66), ('regression: call ahead but opposite direction', {'floor': 2, 'dir': 'up', 'target': 8, 'call_dir': 'down', 'stops': [5, 11], 'per_floor_s': 2, 'stop_s': 10}, 44), ('regression: call at the current floor', {'floor': 5, 'dir': 'up', 'target': 5, 'call_dir': 'up', 'stops': [9], 'per_floor_s': 2, 'stop_s': 10}, 26), ('control 45', {'floor': 2, 'dir': 'down', 'target': 0, 'call_dir': 'down', 'stops': [3, 12, 7, 11], 'per_floor_s': 2, 'stop_s': 8}, 4), ('sampled regression 48', {'floor': 8, 'dir': 'down', 'target': 2, 'call_dir': 'up', 'stops': [8, 7, 4, 6], 'per_floor_s': 3, 'stop_s': 8}, 42), ('control 51', {'floor': 11, 'dir': 'up', 'target': 4, 'call_dir': 'down', 'stops': [], 'per_floor_s': 3, 'stop_s': 12}, 21)]]
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: call behind a down car	`30`	`30`	Passed
regression: stops behind served on return	`42`	`42`	Passed
regression: call ahead but opposite direction	`44`	`44`	Passed
boundary: down car mirrored	`22`	`22`	Passed
regression: call at the current floor	`26`	`26`	Passed
sampled regression 1	`48`	`48`	Passed
control 4	`62`	`62`	Passed
control 7	`24`	`24`	Passed

SHA-256 / 14da907dea6560664d421a54861c9a4af8e37c2565ddca78b9e40129d8c46fb1

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 2026-09-29T14:47:53.957520+00:00.

Case digest / 453dbeac59ab2190837c0745f083c458e93c556bdbdad237ebe6ab4249107e63