FA-67451 / Elevator dispatch scheduling / Open access

Trip flight time from a trapezoidal profile: millisecond rounding · case 01

Predicted trip times are a millisecond short.

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

ROOT CAUSE

Rounding to nearest can round down.

THE FAILURE

Rounding to nearest can round down.

Unsuccessful approach: Truncation always rounds down.

Case contract

heights_mm[i] is the rise from floor i to floor i+1. The trip distance is the sum between the two floors (either direction). With speed vmax (mm/s) and acceleration acc (mm/s^2): if distance*acc >= vmax^2 the car reaches vmax and t = d/vmax + vmax/acc, otherwise t = 2*sqrt(d/acc). Return milliseconds rounded up; zero distance is 0.

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
import math
N = 1
observations = []
def solve(x):
    lo, hi = sorted((x['from'], x['to']))
    d = sum(x['heights_mm'][lo:hi])
    if d == 0:
        return 0
    v = x['vmax']
    a = x['acc']
    if d * a >= v * v:
        t = d / v + v / a
    else:
        t = 2 * math.sqrt(d / a)
    return round(t * 1000)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('boundary: long run at contract speed', {'heights_mm': [4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000], 'from': 0, 'to': 9, 'vmax': 2500, 'acc': 1000}, 16900), ('control 1', {'heights_mm': [5000, 4200, 3500, 4200, 4200, 5000, 3000, 3500, 5000, 4200, 3500], 'from': 7, 'to': 0, 'vmax': 1600, 'acc': 1200}, 19521), ('control 4', {'heights_mm': [3500, 3500, 5000, 3500], 'from': 1, 'to': 1, 'vmax': 4000, 'acc': 600}, 0), ('control 10', {'heights_mm': [4200, 4200, 5000, 4200, 3500, 3000, 3000, 3000, 5000, 3500, 4200, 3500], 'from': 7, 'to': 6, 'vmax': 2500, 'acc': 800}, 3873)], [('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('sampled regression 38', {'heights_mm': [4200, 3500, 4200, 4200, 5000, 3000, 3500, 4200, 3500, 3000, 3500], 'from': 6, 'to': 3, 'vmax': 4000, 'acc': 1200}, 6378), ('control 6', {'heights_mm': [3000, 3500, 3000, 4200, 4200, 5000, 3500, 4200, 5000, 3000, 4200, 3000], 'from': 6, 'to': 4, 'vmax': 1000, 'acc': 600}, 10867), ('boundary: long run at contract speed', {'heights_mm': [4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000], 'from': 0, 'to': 9, 'vmax': 2500, 'acc': 1000}, 16900), ('control 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('control 15', {'heights_mm': [3000, 3500, 3000, 3000, 5000, 3000, 3500, 3000, 3000, 3500], 'from': 4, 'to': 7, 'vmax': 1000, 'acc': 600}, 13167), ('control 18', {'heights_mm': [4200, 3000, 3500, 5000, 3500], 'from': 3, 'to': 4, 'vmax': 1000, 'acc': 800}, 6250)], [('regression: fractional milliseconds', {'heights_mm': [3500, 3500, 3500, 3500], 'from': 0, 'to': 3, 'vmax': 1600, 'acc': 600}, 9230), ('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('sampled regression 48', {'heights_mm': [5000, 3000, 3500, 3000, 3000, 3500, 3500, 3000, 5000, 3500], 'from': 9, 'to': 8, 'vmax': 4000, 'acc': 1000}, 4473), ('control 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('boundary: same floor', {'heights_mm': [3000, 3000, 3000], 'from': 2, 'to': 2, 'vmax': 2500, 'acc': 1000}, 0), ('control 23', {'heights_mm': [5000, 3000, 3000, 4200, 4200, 3500, 3000], 'from': 1, 'to': 0, 'vmax': 1600, 'acc': 1000}, 4725), ('control 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('control 29', {'heights_mm': [3000, 3000, 3500, 3500, 3000, 4200, 3500, 3000, 3000, 4200, 3500, 5000], 'from': 0, 'to': 4, 'vmax': 1000, 'acc': 1000}, 14000)], [('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('regression: fractional milliseconds', {'heights_mm': [3500, 3500, 3500, 3500], 'from': 0, 'to': 3, 'vmax': 1600, 'acc': 600}, 9230), ('sampled regression 72', {'heights_mm': [3500, 3000, 3000, 3500, 5000, 5000, 3000, 3500, 3500, 4200, 3500, 3500], 'from': 8, 'to': 9, 'vmax': 1000, 'acc': 1200}, 4334), ('sampled regression 22', {'heights_mm': [3500, 3500, 5000, 4200, 3000, 5000, 5000, 3000], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 600}, 6929), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('control 34', {'heights_mm': [3000, 5000, 3500, 4200, 3500, 3000, 3500], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 800}, 6205), ('sampled regression 37', {'heights_mm': [3000, 3000, 5000, 3000, 5000], 'from': 2, 'to': 4, 'vmax': 1000, 'acc': 1200}, 8834), ('sampled regression 40', {'heights_mm': [3000, 3500, 3500, 5000], 'from': 0, 'to': 2, 'vmax': 1600, 'acc': 1000}, 5663)], [('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('control 34', {'heights_mm': [3000, 5000, 3500, 4200, 3500, 3000, 3500], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 800}, 6205), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 45', {'heights_mm': [5000, 3500, 3000, 3500, 4200, 3000, 3500, 3500, 3500, 4200], 'from': 3, 'to': 8, 'vmax': 1000, 'acc': 1200}, 18534), ('sampled regression 48', {'heights_mm': [5000, 3000, 3500, 3000, 3000, 3500, 3500, 3000, 5000, 3500], 'from': 9, 'to': 8, 'vmax': 4000, 'acc': 1000}, 4473), ('control 51', {'heights_mm': [4200, 4200, 3000, 5000, 5000, 5000, 3500], 'from': 6, 'to': 5, 'vmax': 4000, 'acc': 800}, 5000)]]
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: one floor up	`3464`	`3465`	Failed
sampled regression 7	`7163`	`7164`	Failed
boundary: short hop without reaching speed	`3873`	`3873`	Passed
boundary: downward trip	`5580`	`5580`	Passed
boundary: long run at contract speed	`16900`	`16900`	Passed
control 1	`19521`	`19521`	Passed
control 4	`0`	`0`	Passed
control 10	`3873`	`3873`	Passed

SHA-256 / e8181e578184887b7da12045f59b0d784c69e7ceab185630d658b96999ef14f0

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    lo, hi = sorted((x['from'], x['to']))
    d = sum(x['heights_mm'][lo:hi])
    if d == 0:
        return 0
    v = x['vmax']
    a = x['acc']
    if d * a >= v * v:
        t = d / v + v / a
    else:
        t = 2 * math.sqrt(d / a)
    return int(t * 1000)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('boundary: long run at contract speed', {'heights_mm': [4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000], 'from': 0, 'to': 9, 'vmax': 2500, 'acc': 1000}, 16900), ('control 1', {'heights_mm': [5000, 4200, 3500, 4200, 4200, 5000, 3000, 3500, 5000, 4200, 3500], 'from': 7, 'to': 0, 'vmax': 1600, 'acc': 1200}, 19521), ('control 4', {'heights_mm': [3500, 3500, 5000, 3500], 'from': 1, 'to': 1, 'vmax': 4000, 'acc': 600}, 0), ('control 10', {'heights_mm': [4200, 4200, 5000, 4200, 3500, 3000, 3000, 3000, 5000, 3500, 4200, 3500], 'from': 7, 'to': 6, 'vmax': 2500, 'acc': 800}, 3873)], [('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('sampled regression 38', {'heights_mm': [4200, 3500, 4200, 4200, 5000, 3000, 3500, 4200, 3500, 3000, 3500], 'from': 6, 'to': 3, 'vmax': 4000, 'acc': 1200}, 6378), ('control 6', {'heights_mm': [3000, 3500, 3000, 4200, 4200, 5000, 3500, 4200, 5000, 3000, 4200, 3000], 'from': 6, 'to': 4, 'vmax': 1000, 'acc': 600}, 10867), ('boundary: long run at contract speed', {'heights_mm': [4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000, 4000], 'from': 0, 'to': 9, 'vmax': 2500, 'acc': 1000}, 16900), ('control 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('control 15', {'heights_mm': [3000, 3500, 3000, 3000, 5000, 3000, 3500, 3000, 3000, 3500], 'from': 4, 'to': 7, 'vmax': 1000, 'acc': 600}, 13167), ('control 18', {'heights_mm': [4200, 3000, 3500, 5000, 3500], 'from': 3, 'to': 4, 'vmax': 1000, 'acc': 800}, 6250)], [('regression: fractional milliseconds', {'heights_mm': [3500, 3500, 3500, 3500], 'from': 0, 'to': 3, 'vmax': 1600, 'acc': 600}, 9230), ('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('sampled regression 48', {'heights_mm': [5000, 3000, 3500, 3000, 3000, 3500, 3500, 3000, 5000, 3500], 'from': 9, 'to': 8, 'vmax': 4000, 'acc': 1000}, 4473), ('control 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('boundary: same floor', {'heights_mm': [3000, 3000, 3000], 'from': 2, 'to': 2, 'vmax': 2500, 'acc': 1000}, 0), ('control 23', {'heights_mm': [5000, 3000, 3000, 4200, 4200, 3500, 3000], 'from': 1, 'to': 0, 'vmax': 1600, 'acc': 1000}, 4725), ('control 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('control 29', {'heights_mm': [3000, 3000, 3500, 3500, 3000, 4200, 3500, 3000, 3000, 4200, 3500, 5000], 'from': 0, 'to': 4, 'vmax': 1000, 'acc': 1000}, 14000)], [('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('regression: fractional milliseconds', {'heights_mm': [3500, 3500, 3500, 3500], 'from': 0, 'to': 3, 'vmax': 1600, 'acc': 600}, 9230), ('sampled regression 72', {'heights_mm': [3500, 3000, 3000, 3500, 5000, 5000, 3000, 3500, 3500, 4200, 3500, 3500], 'from': 8, 'to': 9, 'vmax': 1000, 'acc': 1200}, 4334), ('sampled regression 22', {'heights_mm': [3500, 3500, 5000, 4200, 3000, 5000, 5000, 3000], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 600}, 6929), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('control 34', {'heights_mm': [3000, 5000, 3500, 4200, 3500, 3000, 3500], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 800}, 6205), ('sampled regression 37', {'heights_mm': [3000, 3000, 5000, 3000, 5000], 'from': 2, 'to': 4, 'vmax': 1000, 'acc': 1200}, 8834), ('sampled regression 40', {'heights_mm': [3000, 3500, 3500, 5000], 'from': 0, 'to': 2, 'vmax': 1600, 'acc': 1000}, 5663)], [('regression: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('regression: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('control 34', {'heights_mm': [3000, 5000, 3500, 4200, 3500, 3000, 3500], 'from': 3, 'to': 5, 'vmax': 4000, 'acc': 800}, 6205), ('boundary: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 45', {'heights_mm': [5000, 3500, 3000, 3500, 4200, 3000, 3500, 3500, 3500, 4200], 'from': 3, 'to': 8, 'vmax': 1000, 'acc': 1200}, 18534), ('sampled regression 48', {'heights_mm': [5000, 3000, 3500, 3000, 3000, 3500, 3500, 3000, 5000, 3500], 'from': 9, 'to': 8, 'vmax': 4000, 'acc': 1000}, 4473), ('control 51', {'heights_mm': [4200, 4200, 3000, 5000, 5000, 5000, 3500], 'from': 6, 'to': 5, 'vmax': 4000, 'acc': 800}, 5000)]]
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: one floor up	`3464`	`3465`	Failed
sampled regression 7	`7163`	`7164`	Failed
boundary: short hop without reaching speed	`3872`	`3873`	Failed
boundary: downward trip	`5580`	`5580`	Passed
boundary: long run at contract speed	`16900`	`16900`	Passed
control 1	`19520`	`19521`	Failed
control 4	`0`	`0`	Passed
control 10	`3872`	`3873`	Failed

SHA-256 / 918b673022b465c094cd8cf7c3e6cde71374376840330de918eaf0fc68f150ac

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

Stipulated toy 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 2026-09-29T14:47:53.052384+00:00.

Case digest / df6ae1b64c237b116c12ccc99d97d0a987e4b77a47ced33995f6af659c0c7440