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FA-85771 / Ride-hailing fare and surge pricing / Open access

Segments exactly at the switch speed billed by time · case 01

Traffic moving at exactly 5 m/s is billed on the clock.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The mode test is strict.

THE FAILURE

The mode test is strict.

Unsuccessful approach: Excluding zero-duration segments bills their distance as zero time.

Case contract

A single-tariff taximeter bills each segment [seconds, meters] by distance when its speed is at least v m/s (meters >= v*seconds, so a zero-duration movement bills distance) and by time otherwise, never both. Charges accumulate exactly (per_km per 1000 m, per_hour per 3600 s) and the total is rounded half up to a cent once, then the flag fall is added.

Why this case matters

Ride-hailing prices are computed per trip at scale; ordering, unit and boundary slips become systematic over- or under-charging.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from fractions import Fraction
N = 1
observations = []
def solve(segments, rate):
    acc = Fraction(0)
    for dt, dm in segments:
        if dm > rate['v'] * dt:
            acc += Fraction(dm * rate['per_km'], 1000)
        else:
            acc += Fraction(dt * rate['per_hour'], 3600)
    cents = int(acc * 2 + 1) // 2
    return rate['flag'] + cents
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: switch speed boundary', [[[10, 50]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   402),
  ('partial repair probe: switch speed boundary',
   [[[0, 7], [10, 20], [1, 7]], {'flag': 390, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 403),
  ('second regression',
   [[[30, 60], [0, 3], [0, 0], [10, 0], [10, 53], [30, 7]],
    {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   390),
  ('normal control 1',
   [[[10, 49], [10, 0], [5, 24], [10, 53], [0, 0]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}],
   338),
  ('normal control 2',
   [[[1, 11], [30, 330], [0, 0], [30, 149]], {'flag': 300, 'per_hour': 4150, 'per_km': 230, 'v': 5}], 413),
  ('normal control 3', [[[1, 7], [10, 49]], {'flag': 390, 'per_hour': 3900, 'per_km': 230, 'v': 5}], 402),
  ('normal control 4', [[[1, 8]], {'flag': 390, 'per_hour': 4150, 'per_km': 245, 'v': 5}], 392)],
 [('regression: switch speed boundary',
   [[[0, 0], [5, 24], [1, 8], [1, 11], [10, 50]], {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   321),
  ('partial repair probe: switch speed boundary',
   [[[30, 150], [10, 0], [30, 153], [0, 7]], {'flag': 390, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 463),
  ('second regression',
   [[[30, 7], [30, 149], [10, 50], [10, 49], [5, 7]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   484),
  ('normal control 1', [[[0, 0]], {'flag': 390, 'per_hour': 4150, 'per_km': 230, 'v': 5}], 390),
  ('normal control 2', [[[30, 149], [10, 53]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 435),
  ('normal control 3', [[[1, 0], [10, 0]], {'flag': 300, 'per_hour': 3900, 'per_km': 230, 'v': 5}], 312),
  ('normal control 4', [[[1, 5], [10, 110], [5, 24]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   418)],
 [('regression: switch speed boundary',
   [[[10, 110], [1, 5], [0, 3], [5, 55]], {'flag': 390, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 424),
  ('partial repair probe: switch speed boundary',
   [[[30, 7], [10, 0], [0, 0], [30, 153], [30, 0], [0, 7]],
    {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   407),
  ('second regression',
   [[[0, 3], [5, 25], [10, 0], [0, 7], [1, 7]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}],
   320),
  ('normal control 1', [[[30, 149], [0, 0]], {'flag': 390, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 420),
  ('normal control 2', [[[10, 110], [10, 7]], {'flag': 300, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 332),
  ('normal control 3', [[[30, 60], [1, 7], [0, 0]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   424),
  ('normal control 4', [[[5, 0], [5, 0], [1, 2]], {'flag': 390, 'per_hour': 4150, 'per_km': 230, 'v': 5}],
   403)],
 [('regression: switch speed boundary',
   [[[10, 0], [30, 0], [10, 50], [30, 60], [5, 55], [5, 24]],
    {'flag': 390, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   489),
  ('partial repair probe: switch speed boundary',
   [[[0, 7], [30, 149], [10, 7], [30, 60], [0, 0], [30, 149]],
    {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}],
   491),
  ('second regression',
   [[[10, 20], [1, 11], [5, 10], [30, 7], [0, 0], [0, 7]],
    {'flag': 390, 'per_hour': 4150, 'per_km': 245, 'v': 5}],
   446),
  ('normal control 1',
   [[[1, 5], [1, 8], [5, 25], [5, 10], [0, 0], [10, 20]],
    {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   414),
  ('normal control 2',
   [[[10, 53], [30, 7], [10, 20]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 353),
  ('normal control 3', [[[10, 0], [30, 0]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}], 433),
  ('normal control 4',
   [[[1, 4], [1, 5], [30, 7], [10, 110]], {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 444)],
 [('regression: switch speed boundary',
   [[[1, 5], [10, 110], [10, 50], [1, 7]], {'flag': 300, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 334),
  ('partial repair probe: switch speed boundary',
   [[[0, 7]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 392),
  ('second regression',
   [[[10, 20], [5, 0], [10, 110], [10, 49], [5, 25]], {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   360),
  ('normal control 1', [[[10, 53]], {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 401),
  ('normal control 2', [[[0, 0], [1, 8], [5, 24]], {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   307),
  ('normal control 3', [[[10, 110]], {'flag': 300, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 322),
  ('normal control 4', [[[1, 4], [1, 5]], {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 302)]]
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 fixtureActualExpectedOutcome
regression: switch speed boundary401402Failed
partial repair probe: switch speed boundary403403Passed
second regression390390Passed
normal control 1338338Passed
normal control 2413413Passed
normal control 3402402Passed
normal control 4392392Passed

SHA-256 / 6153f72e95a37b851a1e588666affeca9d596d8616a3d0c804d8f6af992d0a83

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from fractions import Fraction
N = 1
observations = []
def solve(segments, rate):
    acc = Fraction(0)
    for dt, dm in segments:
        if dm >= rate['v'] * dt and dt > 0:
            acc += Fraction(dm * rate['per_km'], 1000)
        else:
            acc += Fraction(dt * rate['per_hour'], 3600)
    cents = int(acc * 2 + 1) // 2
    return rate['flag'] + cents
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: switch speed boundary', [[[10, 50]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   402),
  ('partial repair probe: switch speed boundary',
   [[[0, 7], [10, 20], [1, 7]], {'flag': 390, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 403),
  ('second regression',
   [[[30, 60], [0, 3], [0, 0], [10, 0], [10, 53], [30, 7]],
    {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   390),
  ('normal control 1',
   [[[10, 49], [10, 0], [5, 24], [10, 53], [0, 0]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}],
   338),
  ('normal control 2',
   [[[1, 11], [30, 330], [0, 0], [30, 149]], {'flag': 300, 'per_hour': 4150, 'per_km': 230, 'v': 5}], 413),
  ('normal control 3', [[[1, 7], [10, 49]], {'flag': 390, 'per_hour': 3900, 'per_km': 230, 'v': 5}], 402),
  ('normal control 4', [[[1, 8]], {'flag': 390, 'per_hour': 4150, 'per_km': 245, 'v': 5}], 392)],
 [('regression: switch speed boundary',
   [[[0, 0], [5, 24], [1, 8], [1, 11], [10, 50]], {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   321),
  ('partial repair probe: switch speed boundary',
   [[[30, 150], [10, 0], [30, 153], [0, 7]], {'flag': 390, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 463),
  ('second regression',
   [[[30, 7], [30, 149], [10, 50], [10, 49], [5, 7]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   484),
  ('normal control 1', [[[0, 0]], {'flag': 390, 'per_hour': 4150, 'per_km': 230, 'v': 5}], 390),
  ('normal control 2', [[[30, 149], [10, 53]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 435),
  ('normal control 3', [[[1, 0], [10, 0]], {'flag': 300, 'per_hour': 3900, 'per_km': 230, 'v': 5}], 312),
  ('normal control 4', [[[1, 5], [10, 110], [5, 24]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   418)],
 [('regression: switch speed boundary',
   [[[10, 110], [1, 5], [0, 3], [5, 55]], {'flag': 390, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 424),
  ('partial repair probe: switch speed boundary',
   [[[30, 7], [10, 0], [0, 0], [30, 153], [30, 0], [0, 7]],
    {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   407),
  ('second regression',
   [[[0, 3], [5, 25], [10, 0], [0, 7], [1, 7]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}],
   320),
  ('normal control 1', [[[30, 149], [0, 0]], {'flag': 390, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 420),
  ('normal control 2', [[[10, 110], [10, 7]], {'flag': 300, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 332),
  ('normal control 3', [[[30, 60], [1, 7], [0, 0]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   424),
  ('normal control 4', [[[5, 0], [5, 0], [1, 2]], {'flag': 390, 'per_hour': 4150, 'per_km': 230, 'v': 5}],
   403)],
 [('regression: switch speed boundary',
   [[[10, 0], [30, 0], [10, 50], [30, 60], [5, 55], [5, 24]],
    {'flag': 390, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   489),
  ('partial repair probe: switch speed boundary',
   [[[0, 7], [30, 149], [10, 7], [30, 60], [0, 0], [30, 149]],
    {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}],
   491),
  ('second regression',
   [[[10, 20], [1, 11], [5, 10], [30, 7], [0, 0], [0, 7]],
    {'flag': 390, 'per_hour': 4150, 'per_km': 245, 'v': 5}],
   446),
  ('normal control 1',
   [[[1, 5], [1, 8], [5, 25], [5, 10], [0, 0], [10, 20]],
    {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}],
   414),
  ('normal control 2',
   [[[10, 53], [30, 7], [10, 20]], {'flag': 300, 'per_hour': 3600, 'per_km': 245, 'v': 5}], 353),
  ('normal control 3', [[[10, 0], [30, 0]], {'flag': 390, 'per_hour': 3900, 'per_km': 199, 'v': 5}], 433),
  ('normal control 4',
   [[[1, 4], [1, 5], [30, 7], [10, 110]], {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 444)],
 [('regression: switch speed boundary',
   [[[1, 5], [10, 110], [10, 50], [1, 7]], {'flag': 300, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 334),
  ('partial repair probe: switch speed boundary',
   [[[0, 7]], {'flag': 390, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 392),
  ('second regression',
   [[[10, 20], [5, 0], [10, 110], [10, 49], [5, 25]], {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}],
   360),
  ('normal control 1', [[[10, 53]], {'flag': 390, 'per_hour': 3600, 'per_km': 199, 'v': 5}], 401),
  ('normal control 2', [[[0, 0], [1, 8], [5, 24]], {'flag': 300, 'per_hour': 3600, 'per_km': 230, 'v': 5}],
   307),
  ('normal control 3', [[[10, 110]], {'flag': 300, 'per_hour': 4150, 'per_km': 199, 'v': 5}], 322),
  ('normal control 4', [[[1, 4], [1, 5]], {'flag': 300, 'per_hour': 3900, 'per_km': 245, 'v': 5}], 302)]]
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 fixtureActualExpectedOutcome
regression: switch speed boundary402402Passed
partial repair probe: switch speed boundary402403Failed
second regression389390Failed
normal control 1338338Passed
normal control 2413413Passed
normal control 3402402Passed
normal control 4392392Passed

SHA-256 / d7b5cb3fe11eb71b574c28b9ed13ebadddb80e6e937fb1d1f98addbbad45f61a

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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

A deterministic toy pricing contract stipulated for this example; it does not reproduce the pricing of any real ride-hailing operator or regulator. 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 2026-09-29T14:50:43.510105+00:00.

Case digest / 8ff2ee142893bc59679de811643f7dc2e47805c014e6c8b40f3709da8f22feca