FA-67441 / Elevator dispatch scheduling / Open access

Trip flight time from a trapezoidal profile: cruise formula · case 01

Long trips are predicted too short.

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

ROOT CAUSE

Acceleration and deceleration time are ignored for full-speed trips.

THE FAILURE

Acceleration and deceleration time are ignored for full-speed trips.

Unsuccessful approach: Adding only half the ramp penalty counts one ramp instead of two.

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
    else:
        t = 2 * math.sqrt(d / a)
    return math.ceil(t * 1000 - 1e-9)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 1', {'heights_mm': [5000, 4200, 3500, 4200, 4200, 5000, 3000, 3500, 5000, 4200, 3500], 'from': 7, 'to': 0, 'vmax': 1600, 'acc': 1200}, 19521), ('regression: 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), ('boundary: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('control 4', {'heights_mm': [3500, 3500, 5000, 3500], 'from': 1, 'to': 1, 'vmax': 4000, 'acc': 600}, 0), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('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: 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), ('sampled regression 11', {'heights_mm': [4200, 3500, 5000, 3000, 3000, 5000, 4200], 'from': 3, 'to': 2, 'vmax': 1000, 'acc': 1000}, 6000), ('sampled regression 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: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('boundary: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('sampled regression 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('sampled regression 15', {'heights_mm': [3000, 3500, 3000, 3000, 5000, 3000, 3500, 3000, 3000, 3500], 'from': 4, 'to': 7, 'vmax': 1000, 'acc': 600}, 13167), ('sampled regression 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), ('sampled regression 19', {'heights_mm': [5000, 3500, 3000, 5000, 5000, 4200, 5000, 4200], 'from': 0, 'to': 7, 'vmax': 1000, 'acc': 1000}, 31700), ('sampled regression 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('boundary: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('boundary: same floor', {'heights_mm': [3000, 3000, 3000], 'from': 2, 'to': 2, 'vmax': 2500, 'acc': 1000}, 0), ('sampled regression 23', {'heights_mm': [5000, 3000, 3000, 4200, 4200, 3500, 3000], 'from': 1, 'to': 0, 'vmax': 1600, 'acc': 1000}, 4725), ('sampled regression 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('sampled regression 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: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 30', {'heights_mm': [3500, 4200, 3000, 3500, 3500, 4200, 3500, 5000, 4200, 5000, 4200], 'from': 10, 'to': 9, 'vmax': 1000, 'acc': 800}, 6250), ('sampled regression 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), ('boundary: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('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: 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), ('sampled regression 42', {'heights_mm': [3000, 3500, 4200, 5000, 5000], 'from': 3, 'to': 1, 'vmax': 1600, 'acc': 800}, 6813), ('sampled regression 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('regression: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('sampled regression 45', {'heights_mm': [5000, 3500, 3000, 3500, 4200, 3000, 3500, 3500, 3500, 4200], 'from': 3, 'to': 8, 'vmax': 1000, 'acc': 1200}, 18534), ('control 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: downward trip	`3080`	`5580`	Failed
sampled regression 1	`18188`	`19521`	Failed
regression: long run at contract speed	`14400`	`16900`	Failed
boundary: one floor up	`3465`	`3465`	Passed
boundary: short hop without reaching speed	`3873`	`3873`	Passed
control 4	`0`	`0`	Passed
sampled regression 7	`5080`	`7164`	Failed
control 10	`3873`	`3873`	Passed

SHA-256 / ab7587e3a891b1f2a4a1e17c991f7469a787b44e8bb85afdde390c74ddbaf889

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 / (2 * a)
    else:
        t = 2 * math.sqrt(d / a)
    return math.ceil(t * 1000 - 1e-9)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 1', {'heights_mm': [5000, 4200, 3500, 4200, 4200, 5000, 3000, 3500, 5000, 4200, 3500], 'from': 7, 'to': 0, 'vmax': 1600, 'acc': 1200}, 19521), ('regression: 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), ('boundary: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('control 4', {'heights_mm': [3500, 3500, 5000, 3500], 'from': 1, 'to': 1, 'vmax': 4000, 'acc': 600}, 0), ('sampled regression 7', {'heights_mm': [3500, 3500, 4200, 5000, 3500], 'from': 4, 'to': 1, 'vmax': 2500, 'acc': 1200}, 7164), ('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: 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), ('sampled regression 11', {'heights_mm': [4200, 3500, 5000, 3000, 3000, 5000, 4200], 'from': 3, 'to': 2, 'vmax': 1000, 'acc': 1000}, 6000), ('sampled regression 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: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('boundary: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('sampled regression 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('sampled regression 15', {'heights_mm': [3000, 3500, 3000, 3000, 5000, 3000, 3500, 3000, 3000, 3500], 'from': 4, 'to': 7, 'vmax': 1000, 'acc': 600}, 13167), ('sampled regression 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), ('sampled regression 19', {'heights_mm': [5000, 3500, 3000, 5000, 5000, 4200, 5000, 4200], 'from': 0, 'to': 7, 'vmax': 1000, 'acc': 1000}, 31700), ('sampled regression 12', {'heights_mm': [3000, 5000, 3000, 5000, 4200, 5000, 3000, 4200, 4200, 3500], 'from': 5, 'to': 1, 'vmax': 1000, 'acc': 600}, 18867), ('boundary: between the two regimes', {'heights_mm': [3500, 3500, 3500, 3500, 3500, 3500], 'from': 0, 'to': 2, 'vmax': 2500, 'acc': 800}, 5917), ('boundary: same floor', {'heights_mm': [3000, 3000, 3000], 'from': 2, 'to': 2, 'vmax': 2500, 'acc': 1000}, 0), ('sampled regression 23', {'heights_mm': [5000, 3000, 3000, 4200, 4200, 3500, 3000], 'from': 1, 'to': 0, 'vmax': 1600, 'acc': 1000}, 4725), ('sampled regression 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('sampled regression 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: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('sampled regression 30', {'heights_mm': [3500, 4200, 3000, 3500, 3500, 4200, 3500, 5000, 4200, 5000, 4200], 'from': 10, 'to': 9, 'vmax': 1000, 'acc': 800}, 6250), ('sampled regression 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), ('boundary: one floor up', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 0, 'to': 1, 'vmax': 2500, 'acc': 1000}, 3465), ('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: 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), ('sampled regression 42', {'heights_mm': [3000, 3500, 4200, 5000, 5000], 'from': 3, 'to': 1, 'vmax': 1600, 'acc': 800}, 6813), ('sampled regression 26', {'heights_mm': [4200, 5000, 4200, 4200, 3000, 3500, 3500, 3500], 'from': 7, 'to': 0, 'vmax': 4000, 'acc': 1000}, 10900), ('regression: downward trip', {'heights_mm': [3000, 3500, 4200, 5000], 'from': 3, 'to': 1, 'vmax': 2500, 'acc': 1000}, 5580), ('boundary: short hop without reaching speed', {'heights_mm': [3000, 3000, 3000, 3000, 3000], 'from': 1, 'to': 2, 'vmax': 4000, 'acc': 800}, 3873), ('sampled regression 45', {'heights_mm': [5000, 3500, 3000, 3500, 4200, 3000, 3500, 3500, 3500, 4200], 'from': 3, 'to': 8, 'vmax': 1000, 'acc': 1200}, 18534), ('control 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: downward trip	`4330`	`5580`	Failed
sampled regression 1	`18855`	`19521`	Failed
regression: long run at contract speed	`15650`	`16900`	Failed
boundary: one floor up	`3465`	`3465`	Passed
boundary: short hop without reaching speed	`3873`	`3873`	Passed
control 4	`0`	`0`	Passed
sampled regression 7	`6122`	`7164`	Failed
control 10	`3873`	`3873`	Passed

SHA-256 / 7f49d9c62ed4172ed009b80e14d3342bf134b53b49c02bd75f7054b9cab6ce1e

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 2026-09-29T14:47:52.943914+00:00.

Case digest / 83051d3b27abc6035f0c379e9f369bb61bcf56cc30cfc88076cd021b372dbd98