FAILURE MAP
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FA-84726 / Betting odds conversion / Open access

Dead-heat net pool not split between winners · case 01

Both dead-heated runners are paid from the full net pool.

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

ROOT CAUSE

The net pool is not divided by the number of winners.

VERIFIED REPAIR

Split the net pool equally between the winning runners.

Unsuccessful approach: Dividing the net pool by the combined stakes gives every winner the same dividend.

Case contract

Pari-mutuel win dividend per unit stake. The net pool is pool * (100 - takeout_pct) / 100; with a dead heat it is split equally among the winning runners. Each runner's dividend is its share divided by the stakes on it, broken down to the 10-cent step below (breakage), with a minimum of 1.10. A winner with no stakes gets None. Return dividends as "D.D0" strings in winners order.

Why this case matters

Tote operators compute dividends with takeout, breakage and minimum-dividend rules.

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(pool_cents, takeout_pct, winners):
    net = Fraction(pool_cents) * (100 - Fraction(takeout_pct)) / 100
    share = net
    out = []
    for s in winners:
        if s == 0:
            out.append(None)
            continue
        dimes = math.floor(share / s * 10)
        dimes = max(dimes, 11)
        out.append('%d.%d0' % (dimes // 10, dimes % 10))
    return out
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 single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (50000, '20', [5780, 19643, 10000]),
   ['2.30', '1.10', '1.30']),
  ('variant scenario 1', (20000, '20', [6429]), ['2.40']),
  ('variant scenario 2', (100000, '16', [63045]), ['1.30'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (1234500, '15', [116623, 1500, 315481]),
   ['2.90', '233.10', '1.10']),
  ('variant scenario 1', (1234500, '0', [1197831]), ['1.10']),
  ('variant scenario 2', (250000, '20', [133099, 235040]), ['1.10', '1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (250000, '16', [217934, 1500, 28724]),
   ['1.10', '46.60', '2.40']),
  ('variant scenario 1', (50000, '20', [49163, 50000, 25000]), ['1.10', '1.10', '1.10']),
  ('variant scenario 2', (100000, '15', [39045]), ['2.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '0', [333, 9067]), ['30.00', '1.10']),
  ('variant scenario 1', (1234500, '16', [502220]), ['2.00']),
  ('variant scenario 2', (1234500, '0', [1050059]), ['1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '20', [333, 2307, 4298]), ['16.00', '2.30', '1.20']),
  ('variant scenario 1', (100000, '0', [52164]), ['1.90']),
  ('variant scenario 2', (100000, '15', [45964]), ['1.80'])]]
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 fixtureActualExpectedOutcome
control single winner['3.40']['3.40']Passed
boundary breakage down['2.80']['2.80']Passed
boundary minimum dividend['1.10']['1.10']Passed
boundary dead heat split['8.00', '2.00']['4.00', '1.10']Failed
control unbacked winner[None][None]Passed
regression: dead heat pool split['6.90', '2.00', '4.00']['2.30', '1.10', '1.30']Failed
variant scenario 1['2.40']['2.40']Passed
variant scenario 2['1.30']['1.30']Passed

SHA-256 / f3603fde77f6729727e6d2d1db74db081ad379fc3d623501299b594d5160085d

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(pool_cents, takeout_pct, winners):
    net = Fraction(pool_cents) * (100 - Fraction(takeout_pct)) / 100
    share = net / len(winners)
    out = []
    for s in winners:
        if s == 0:
            out.append(None)
            continue
        dimes = math.floor(net / sum(winners) * 10)
        dimes = max(dimes, 11)
        out.append('%d.%d0' % (dimes // 10, dimes % 10))
    return out
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 single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (50000, '20', [5780, 19643, 10000]),
   ['2.30', '1.10', '1.30']),
  ('variant scenario 1', (20000, '20', [6429]), ['2.40']),
  ('variant scenario 2', (100000, '16', [63045]), ['1.30'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (1234500, '15', [116623, 1500, 315481]),
   ['2.90', '233.10', '1.10']),
  ('variant scenario 1', (1234500, '0', [1197831]), ['1.10']),
  ('variant scenario 2', (250000, '20', [133099, 235040]), ['1.10', '1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (250000, '16', [217934, 1500, 28724]),
   ['1.10', '46.60', '2.40']),
  ('variant scenario 1', (50000, '20', [49163, 50000, 25000]), ['1.10', '1.10', '1.10']),
  ('variant scenario 2', (100000, '15', [39045]), ['2.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '0', [333, 9067]), ['30.00', '1.10']),
  ('variant scenario 1', (1234500, '16', [502220]), ['2.00']),
  ('variant scenario 2', (1234500, '0', [1050059]), ['1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '20', [333, 2307, 4298]), ['16.00', '2.30', '1.20']),
  ('variant scenario 1', (100000, '0', [52164]), ['1.90']),
  ('variant scenario 2', (100000, '15', [45964]), ['1.80'])]]
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 fixtureActualExpectedOutcome
control single winner['3.40']['3.40']Passed
boundary breakage down['2.80']['2.80']Passed
boundary minimum dividend['1.10']['1.10']Passed
boundary dead heat split['1.60', '1.60']['4.00', '1.10']Failed
control unbacked winner[None][None]Passed
regression: dead heat pool split['1.10', '1.10', '1.10']['2.30', '1.10', '1.30']Failed
variant scenario 1['2.40']['2.40']Passed
variant scenario 2['1.30']['1.30']Passed

SHA-256 / 64fd088de657f85e107fefbfcfbd99550798620cbb9ce6264227b28521d86fb4

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(pool_cents, takeout_pct, winners):
    net = Fraction(pool_cents) * (100 - Fraction(takeout_pct)) / 100
    share = net / len(winners)
    out = []
    for s in winners:
        if s == 0:
            out.append(None)
            continue
        dimes = math.floor(share / s * 10)
        dimes = max(dimes, 11)
        out.append('%d.%d0' % (dimes // 10, dimes % 10))
    return out
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 single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (50000, '20', [5780, 19643, 10000]),
   ['2.30', '1.10', '1.30']),
  ('variant scenario 1', (20000, '20', [6429]), ['2.40']),
  ('variant scenario 2', (100000, '16', [63045]), ['1.30'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (1234500, '15', [116623, 1500, 315481]),
   ['2.90', '233.10', '1.10']),
  ('variant scenario 1', (1234500, '0', [1197831]), ['1.10']),
  ('variant scenario 2', (250000, '20', [133099, 235040]), ['1.10', '1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split',
   (250000, '16', [217934, 1500, 28724]),
   ['1.10', '46.60', '2.40']),
  ('variant scenario 1', (50000, '20', [49163, 50000, 25000]), ['1.10', '1.10', '1.10']),
  ('variant scenario 2', (100000, '15', [39045]), ['2.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '0', [333, 9067]), ['30.00', '1.10']),
  ('variant scenario 1', (1234500, '16', [502220]), ['2.00']),
  ('variant scenario 2', (1234500, '0', [1050059]), ['1.10'])],
 [('control single winner', (100000, '15', [25000]), ['3.40']),
  ('boundary breakage down', (100000, '16', [30000]), ['2.80']),
  ('boundary minimum dividend', (100000, '20', [90000]), ['1.10']),
  ('boundary dead heat split', (100000, '20', [10000, 40000]), ['4.00', '1.10']),
  ('control unbacked winner', (100000, '15', [0]), [None]),
  ('regression: dead heat pool split', (20000, '20', [333, 2307, 4298]), ['16.00', '2.30', '1.20']),
  ('variant scenario 1', (100000, '0', [52164]), ['1.90']),
  ('variant scenario 2', (100000, '15', [45964]), ['1.80'])]]
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 fixtureActualExpectedOutcome
control single winner['3.40']['3.40']Passed
boundary breakage down['2.80']['2.80']Passed
boundary minimum dividend['1.10']['1.10']Passed
boundary dead heat split['4.00', '1.10']['4.00', '1.10']Passed
control unbacked winner[None][None]Passed
regression: dead heat pool split['2.30', '1.10', '1.30']['2.30', '1.10', '1.30']Passed
variant scenario 1['2.40']['2.40']Passed
variant scenario 2['1.30']['1.30']Passed

SHA-256 / 199e55460c1ff29333020be9b64979edb5eef303a04f26a6bdfbee3dd18b66fc

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 2026-09-29T14:50:33.766557+00:00.

Case digest / 8047a1d66e5512bf85723b2a458d5391858ffcbb06bdb63ca3d0c4b54bf4ddf1