FA-84606 / Betting odds conversion / Open access
Prices below the ladder minimum not rejected · case 01
A 1.00 request crashes the snapping loop or the 1.01 minimum is rejected.
ROOT CAUSE
The lower range check allows 1.00.
VERIFIED REPAIR
Reject only prices below 1.01 or above 1000.
Unsuccessful approach: Rejecting 1.01 itself removes the lowest valid tick.
Case contract
Snap a requested price onto an exchange tick ladder. Bands in hundredths [lo, hi, step]: [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)]. Prices outside 1.01..1000 return "invalid". A back request rounds down to a valid tick and a lay request rounds up (ticks counted from the band lower bound). Return the tick as "%d.%02d".
Why this case matters
Exchange order entry must snap arbitrary prices to valid ticks in the customer-safe direction.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
from fractions import Fraction
import math
N = 1
observations = []
def solve(price, side):
BANDS = [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)]
c = Fraction(price) * 100
if c < 100 or c > 100000:
return 'invalid'
for lo, hi, step in BANDS:
if lo <= c < hi:
k = (c - lo) / step
k = math.floor(k) if side == 'back' else math.ceil(k)
v = lo + k * step
break
return '%d.%02d' % (v // 100, v % 100)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
def run(args):
try:
return solve(*args)
except Exception as exc:
return 'raised ' + type(exc).__name__
cases = [[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.43', 'back'), '3.40'),
('variant scenario 2', ('715.39', 'lay'), '720.00')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('23.13', 'lay'), '24.00'),
('variant scenario 2', ('2.94', 'back'), '2.94')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('variant scenario 1', ('20.82', 'lay'), '21.00'),
('variant scenario 2', ('2.89', 'lay'), '2.90')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.05', 'lay'), '3.05'),
('variant scenario 2', ('3.46', 'lay'), '3.50')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('1.30', 'back'), '1.30'),
('variant scenario 2', ('16.96', 'back'), '16.50')]]
for label, args, expected in cases[N - 1]:
check(label, run(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 |
|---|---|---|---|
| control on-tick price | 2.50 | 2.50 | Passed |
| boundary back rounds down | 3.00 | 3.00 | Passed |
| boundary lay rounds up | 3.05 | 3.05 | Passed |
| boundary lay rounds into next band | 2.00 | 2.00 | Passed |
| boundary below ladder | raised UnboundLocalError | invalid | Failed |
| control top of ladder | 1000.00 | 1000.00 | Passed |
| regression: ladder range | raised UnboundLocalError | invalid | Failed |
| regression: ladder range | 1.01 | 1.01 | Passed |
| variant scenario 1 | 3.40 | 3.40 | Passed |
| variant scenario 2 | 720.00 | 720.00 | Passed |
SHA-256 / 84f6399fd62e958472d48f610972978466e8d48915ff3f5d886b272b3e705b03
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
from fractions import Fraction
import math
N = 1
observations = []
def solve(price, side):
BANDS = [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)]
c = Fraction(price) * 100
if c <= 101 or c > 100000:
return 'invalid'
for lo, hi, step in BANDS:
if lo <= c < hi:
k = (c - lo) / step
k = math.floor(k) if side == 'back' else math.ceil(k)
v = lo + k * step
break
return '%d.%02d' % (v // 100, v % 100)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
def run(args):
try:
return solve(*args)
except Exception as exc:
return 'raised ' + type(exc).__name__
cases = [[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.43', 'back'), '3.40'),
('variant scenario 2', ('715.39', 'lay'), '720.00')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('23.13', 'lay'), '24.00'),
('variant scenario 2', ('2.94', 'back'), '2.94')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('variant scenario 1', ('20.82', 'lay'), '21.00'),
('variant scenario 2', ('2.89', 'lay'), '2.90')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.05', 'lay'), '3.05'),
('variant scenario 2', ('3.46', 'lay'), '3.50')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('1.30', 'back'), '1.30'),
('variant scenario 2', ('16.96', 'back'), '16.50')]]
for label, args, expected in cases[N - 1]:
check(label, run(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 |
|---|---|---|---|
| control on-tick price | 2.50 | 2.50 | Passed |
| boundary back rounds down | 3.00 | 3.00 | Passed |
| boundary lay rounds up | 3.05 | 3.05 | Passed |
| boundary lay rounds into next band | 2.00 | 2.00 | Passed |
| boundary below ladder | invalid | invalid | Passed |
| control top of ladder | 1000.00 | 1000.00 | Passed |
| regression: ladder range | invalid | invalid | Passed |
| regression: ladder range | invalid | 1.01 | Failed |
| variant scenario 1 | 3.40 | 3.40 | Passed |
| variant scenario 2 | 720.00 | 720.00 | Passed |
SHA-256 / 64d9a87fbba1b5607b896dbfc3ff5d17a30a53c74907c0c6ac8818b3d8e031a8
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
from fractions import Fraction
import math
N = 1
observations = []
def solve(price, side):
BANDS = [(101, 200, 1), (200, 300, 2), (300, 400, 5), (400, 600, 10), (600, 1000, 20), (1000, 2000, 50), (2000, 3000, 100), (3000, 5000, 200), (5000, 10000, 500), (10000, 100001, 1000)]
c = Fraction(price) * 100
if c < 101 or c > 100000:
return 'invalid'
for lo, hi, step in BANDS:
if lo <= c < hi:
k = (c - lo) / step
k = math.floor(k) if side == 'back' else math.ceil(k)
v = lo + k * step
break
return '%d.%02d' % (v // 100, v % 100)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
def run(args):
try:
return solve(*args)
except Exception as exc:
return 'raised ' + type(exc).__name__
cases = [[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.43', 'back'), '3.40'),
('variant scenario 2', ('715.39', 'lay'), '720.00')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('23.13', 'lay'), '24.00'),
('variant scenario 2', ('2.94', 'back'), '2.94')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('variant scenario 1', ('20.82', 'lay'), '21.00'),
('variant scenario 2', ('2.89', 'lay'), '2.90')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.00', 'back'), 'invalid'),
('regression: ladder range', ('1.01', 'back'), '1.01'),
('variant scenario 1', ('3.05', 'lay'), '3.05'),
('variant scenario 2', ('3.46', 'lay'), '3.50')],
[('control on-tick price', ('2.50', 'back'), '2.50'),
('boundary back rounds down', ('3.03', 'back'), '3.00'),
('boundary lay rounds up', ('3.03', 'lay'), '3.05'),
('boundary lay rounds into next band', ('1.995', 'lay'), '2.00'),
('boundary below ladder', ('1.00', 'back'), 'invalid'),
('control top of ladder', ('1000', 'lay'), '1000.00'),
('regression: ladder range', ('1.01', 'lay'), '1.01'),
('regression: ladder range', ('1.00', 'lay'), 'invalid'),
('variant scenario 1', ('1.30', 'back'), '1.30'),
('variant scenario 2', ('16.96', 'back'), '16.50')]]
for label, args, expected in cases[N - 1]:
check(label, run(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 |
|---|---|---|---|
| control on-tick price | 2.50 | 2.50 | Passed |
| boundary back rounds down | 3.00 | 3.00 | Passed |
| boundary lay rounds up | 3.05 | 3.05 | Passed |
| boundary lay rounds into next band | 2.00 | 2.00 | Passed |
| boundary below ladder | invalid | invalid | Passed |
| control top of ladder | 1000.00 | 1000.00 | Passed |
| regression: ladder range | invalid | invalid | Passed |
| regression: ladder range | 1.01 | 1.01 | Passed |
| variant scenario 1 | 3.40 | 3.40 | Passed |
| variant scenario 2 | 720.00 | 720.00 | Passed |
SHA-256 / ea83b808a3e6333b6d1fdbc975bf82a723c9cb0f12bfbc04b5095a63f53dac18
Verification & scope
Stipulated, bounded toy contract stated in the contract field; not a claim of conformance with any operator, exchange or regulator rule set. 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 2026-09-29T14:50:32.564191+00:00.
Case digest / b5987464e7b470541d52ba3da637c7ca01be6b8fbc69a3669e2823def33f145f