FAILURE MAP
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FA-63276 / Insurance premium rating / Open access

Mid-term endorsement pro-rata premium: Endorsements effective on expiry are accepted · case 01

An endorsement dated on the expiration date returns zero instead of an error.

Verified by executionVariant 1 · 11 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The upper date bound is inclusive.

THE FAILURE

The upper date bound is inclusive.

Unsuccessful approach: Rejecting the last in-force day also blocks legal endorsements.

Case contract

Input start, end (days), annual premium, endorsements [[effective day, new annual premium]]. Dates must satisfy start<=d<end and be non-decreasing, else 'invalid endorsement date'. Each endorsement charges (new-current)*(end-d)/(end-start) rounded half away from zero, and the new premium becomes current.

Why this case matters

Endorsement premiums must chain from the latest in-force rate and prorate on the actual term length.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
from fractions import Fraction
N = 1
observations = []
def solve(x):
    s=x['start']; e=x['end']; T=e-s
    def r(v): return math.floor(v+Fraction(1,2)) if v>=0 else -math.floor(-v+Fraction(1,2))
    cur=x['annual']; out=[]; last=s
    for d,new in x['endorsements']:
        if d<s or d>e or d<last: return 'invalid endorsement date'
        out.append(r(Fraction((new-cur)*(e-d),T)))
        cur=new; last=d
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['single increase', {'start': 2912, 'end': 3277, 'annual': 228520, 'endorsements': [[3043, 390228]]}, [103670]], ['increase then decrease', {'start': 477, 'end': 842, 'annual': 136883, 'endorsements': [[562, 340860], [681, 77377]]}, [156476, -116221]], ['decrease then partial restore', {'start': 2037, 'end': 2402, 'annual': 100000, 'endorsements': [[2109, 40001], [2277, 63890]]}, [-48164, 8181]], ['leap-year term', {'start': 2320, 'end': 2686, 'annual': 138690, 'endorsements': [[2497, 161560]]}, [11810]], ['six-month term', {'start': 2269, 'end': 2451, 'annual': 114166, 'endorsements': [[2418, 400299], [2439, 379739]]}, [51881, -1356]], ['endorsement on expiry rejected', {'start': 286, 'end': 651, 'annual': 174243, 'endorsements': [[651, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 962, 'end': 1327, 'annual': 166624, 'endorsements': [[961, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 251, 'end': 616, 'annual': 164047, 'endorsements': [[451, 200000], [351, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 579, 'end': 944, 'annual': 88017, 'endorsements': [[579, 316996]]}, [228979]], ['same-day endorsements', {'start': 17, 'end': 382, 'annual': 194026, 'endorsements': [[137, 250000], [137, 260000]]}, [37572, 6712]], ['last day endorsement', {'start': 2889, 'end': 3254, 'annual': 100000, 'endorsements': [[3253, 255567]]}, [426]]], [['single increase', {'start': 2490, 'end': 2855, 'annual': 104092, 'endorsements': [[2682, 358418]]}, [120544]], ['increase then decrease', {'start': 1761, 'end': 2126, 'annual': 95155, 'endorsements': [[1839, 390602], [1949, 60898]]}, [232310, -159884]], ['decrease then partial restore', {'start': 2809, 'end': 3174, 'annual': 100000, 'endorsements': [[2849, 40002], [3041, 65761]]}, [-53423, 9386]], ['leap-year term', {'start': 2789, 'end': 3155, 'annual': 136600, 'endorsements': [[3052, 310248]]}, [48868]], ['six-month term', {'start': 1197, 'end': 1379, 'annual': 163268, 'endorsements': [[1271, 255330], [1367, 168424]]}, [54630, -5730]], ['endorsement on expiry rejected', {'start': 48, 'end': 413, 'annual': 192511, 'endorsements': [[413, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 1771, 'end': 2136, 'annual': 162702, 'endorsements': [[1770, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 2865, 'end': 3230, 'annual': 261177, 'endorsements': [[3065, 200000], [2965, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 1467, 'end': 1832, 'annual': 116027, 'endorsements': [[1467, 190089]]}, [74062]], ['same-day endorsements', {'start': 847, 'end': 1212, 'annual': 109565, 'endorsements': [[967, 250000], [967, 260000]]}, [94265, 6712]], ['last day endorsement', {'start': 2776, 'end': 3141, 'annual': 100000, 'endorsements': [[3140, 396043]]}, [811]]], [['single increase', {'start': 1206, 'end': 1571, 'annual': 166000, 'endorsements': [[1276, 393494]]}, [183865]], ['increase then decrease', {'start': 749, 'end': 1114, 'annual': 280762, 'endorsements': [[848, 343990], [953, 67369]]}, [46078, -122016]], ['decrease then partial restore', {'start': 766, 'end': 1131, 'annual': 100000, 'endorsements': [[803, 40003], [1051, 69438]]}, [-53915, 6452]], ['leap-year term', {'start': 2028, 'end': 2394, 'annual': 148609, 'endorsements': [[2319, 100348]]}, [-9890]], ['six-month term', {'start': 1944, 'end': 2126, 'annual': 124458, 'endorsements': [[2010, 171861], [2114, 388840]]}, [30213, 14306]], ['endorsement on expiry rejected', {'start': 1174, 'end': 1539, 'annual': 115160, 'endorsements': [[1539, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 2665, 'end': 3030, 'annual': 152976, 'endorsements': [[2664, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 1602, 'end': 1967, 'annual': 240101, 'endorsements': [[1802, 200000], [1702, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 908, 'end': 1273, 'annual': 148941, 'endorsements': [[908, 436896]]}, [287955]], ['same-day endorsements', {'start': 1319, 'end': 1684, 'annual': 113258, 'endorsements': [[1439, 250000], [1439, 260000]]}, [91786, 6712]], ['last day endorsement', {'start': 2821, 'end': 3186, 'annual': 100000, 'endorsements': [[3185, 367523]]}, [733]]], [['single increase', {'start': 2447, 'end': 2812, 'annual': 190688, 'endorsements': [[2655, 312597]]}, [52438]], ['increase then decrease', {'start': 1314, 'end': 1679, 'annual': 268062, 'endorsements': [[1335, 344123], [1518, 58352]]}, [71685, -126052]], ['decrease then partial restore', {'start': 1117, 'end': 1482, 'annual': 100000, 'endorsements': [[1159, 40004], [1334, 61238]]}, [-53092, 8610]], ['leap-year term', {'start': 1273, 'end': 1639, 'annual': 241312, 'endorsements': [[1536, 193555]]}, [-13440]], ['six-month term', {'start': 49, 'end': 231, 'annual': 80756, 'endorsements': [[79, 411368], [219, 276361]]}, [276116, -8902]], ['endorsement on expiry rejected', {'start': 2167, 'end': 2532, 'annual': 216523, 'endorsements': [[2532, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 1680, 'end': 2045, 'annual': 258325, 'endorsements': [[1679, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 2653, 'end': 3018, 'annual': 115795, 'endorsements': [[2853, 200000], [2753, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 2438, 'end': 2803, 'annual': 251511, 'endorsements': [[2438, 112887]]}, [-138624]], ['same-day endorsements', {'start': 1751, 'end': 2116, 'annual': 210625, 'endorsements': [[1871, 250000], [1871, 260000]]}, [26430, 6712]], ['last day endorsement', {'start': 1049, 'end': 1414, 'annual': 100000, 'endorsements': [[1413, 290691]]}, [522]]], [['single increase', {'start': 567, 'end': 932, 'annual': 242069, 'endorsements': [[864, 340392]]}, [18318]], ['increase then decrease', {'start': 2519, 'end': 2884, 'annual': 179314, 'endorsements': [[2537, 319903], [2726, 81013]]}, [133656, -103410]], ['decrease then partial restore', {'start': 1092, 'end': 1457, 'annual': 100000, 'endorsements': [[1105, 40005], [1285, 62765]]}, [-57858, 10725]], ['leap-year term', {'start': 820, 'end': 1186, 'annual': 204385, 'endorsements': [[905, 292674]]}, [67785]], ['six-month term', {'start': 1400, 'end': 1582, 'annual': 108639, 'endorsements': [[1481, 441832], [1570, 418671]]}, [184904, -1527]], ['endorsement on expiry rejected', {'start': 936, 'end': 1301, 'annual': 206524, 'endorsements': [[1301, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 983, 'end': 1348, 'annual': 294557, 'endorsements': [[982, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 1953, 'end': 2318, 'annual': 262141, 'endorsements': [[2153, 200000], [2053, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 2741, 'end': 3106, 'annual': 192566, 'endorsements': [[2741, 174344]]}, [-18222]], ['same-day endorsements', {'start': 114, 'end': 479, 'annual': 252584, 'endorsements': [[234, 250000], [234, 260000]]}, [-1734, 6712]], ['last day endorsement', {'start': 1695, 'end': 2060, 'annual': 100000, 'endorsements': [[2059, 111498]]}, [32]]]]
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
single increase[103670][103670]Passed
increase then decrease[156476, -116221][156476, -116221]Passed
decrease then partial restore[-48164, 8181][-48164, 8181]Passed
leap-year term[11810][11810]Passed
six-month term[51881, -1356][51881, -1356]Passed
endorsement on expiry rejected[0]invalid endorsement dateFailed
endorsement before inception rejectedinvalid endorsement dateinvalid endorsement datePassed
out of order rejectedinvalid endorsement dateinvalid endorsement datePassed
inception-day endorsement[228979][228979]Passed
same-day endorsements[37572, 6712][37572, 6712]Passed
last day endorsement[426][426]Passed

SHA-256 / fca10f2e39d1fe7c5d4a5411e7aa31f28a66c52a33fa8d7e1e0a873c350bef93

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
from fractions import Fraction
N = 1
observations = []
def solve(x):
    s=x['start']; e=x['end']; T=e-s
    def r(v): return math.floor(v+Fraction(1,2)) if v>=0 else -math.floor(-v+Fraction(1,2))
    cur=x['annual']; out=[]; last=s
    for d,new in x['endorsements']:
        if d<s or d>=e-1 or d<last: return 'invalid endorsement date'
        out.append(r(Fraction((new-cur)*(e-d),T)))
        cur=new; last=d
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['single increase', {'start': 2912, 'end': 3277, 'annual': 228520, 'endorsements': [[3043, 390228]]}, [103670]], ['increase then decrease', {'start': 477, 'end': 842, 'annual': 136883, 'endorsements': [[562, 340860], [681, 77377]]}, [156476, -116221]], ['decrease then partial restore', {'start': 2037, 'end': 2402, 'annual': 100000, 'endorsements': [[2109, 40001], [2277, 63890]]}, [-48164, 8181]], ['leap-year term', {'start': 2320, 'end': 2686, 'annual': 138690, 'endorsements': [[2497, 161560]]}, [11810]], ['six-month term', {'start': 2269, 'end': 2451, 'annual': 114166, 'endorsements': [[2418, 400299], [2439, 379739]]}, [51881, -1356]], ['endorsement on expiry rejected', {'start': 286, 'end': 651, 'annual': 174243, 'endorsements': [[651, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 962, 'end': 1327, 'annual': 166624, 'endorsements': [[961, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 251, 'end': 616, 'annual': 164047, 'endorsements': [[451, 200000], [351, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 579, 'end': 944, 'annual': 88017, 'endorsements': [[579, 316996]]}, [228979]], ['same-day endorsements', {'start': 17, 'end': 382, 'annual': 194026, 'endorsements': [[137, 250000], [137, 260000]]}, [37572, 6712]], ['last day endorsement', {'start': 2889, 'end': 3254, 'annual': 100000, 'endorsements': [[3253, 255567]]}, [426]]], [['single increase', {'start': 2490, 'end': 2855, 'annual': 104092, 'endorsements': [[2682, 358418]]}, [120544]], ['increase then decrease', {'start': 1761, 'end': 2126, 'annual': 95155, 'endorsements': [[1839, 390602], [1949, 60898]]}, [232310, -159884]], ['decrease then partial restore', {'start': 2809, 'end': 3174, 'annual': 100000, 'endorsements': [[2849, 40002], [3041, 65761]]}, [-53423, 9386]], ['leap-year term', {'start': 2789, 'end': 3155, 'annual': 136600, 'endorsements': [[3052, 310248]]}, [48868]], ['six-month term', {'start': 1197, 'end': 1379, 'annual': 163268, 'endorsements': [[1271, 255330], [1367, 168424]]}, [54630, -5730]], ['endorsement on expiry rejected', {'start': 48, 'end': 413, 'annual': 192511, 'endorsements': [[413, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 1771, 'end': 2136, 'annual': 162702, 'endorsements': [[1770, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 2865, 'end': 3230, 'annual': 261177, 'endorsements': [[3065, 200000], [2965, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 1467, 'end': 1832, 'annual': 116027, 'endorsements': [[1467, 190089]]}, [74062]], ['same-day endorsements', {'start': 847, 'end': 1212, 'annual': 109565, 'endorsements': [[967, 250000], [967, 260000]]}, [94265, 6712]], ['last day endorsement', {'start': 2776, 'end': 3141, 'annual': 100000, 'endorsements': [[3140, 396043]]}, [811]]], [['single increase', {'start': 1206, 'end': 1571, 'annual': 166000, 'endorsements': [[1276, 393494]]}, [183865]], ['increase then decrease', {'start': 749, 'end': 1114, 'annual': 280762, 'endorsements': [[848, 343990], [953, 67369]]}, [46078, -122016]], ['decrease then partial restore', {'start': 766, 'end': 1131, 'annual': 100000, 'endorsements': [[803, 40003], [1051, 69438]]}, [-53915, 6452]], ['leap-year term', {'start': 2028, 'end': 2394, 'annual': 148609, 'endorsements': [[2319, 100348]]}, [-9890]], ['six-month term', {'start': 1944, 'end': 2126, 'annual': 124458, 'endorsements': [[2010, 171861], [2114, 388840]]}, [30213, 14306]], ['endorsement on expiry rejected', {'start': 1174, 'end': 1539, 'annual': 115160, 'endorsements': [[1539, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 2665, 'end': 3030, 'annual': 152976, 'endorsements': [[2664, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 1602, 'end': 1967, 'annual': 240101, 'endorsements': [[1802, 200000], [1702, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 908, 'end': 1273, 'annual': 148941, 'endorsements': [[908, 436896]]}, [287955]], ['same-day endorsements', {'start': 1319, 'end': 1684, 'annual': 113258, 'endorsements': [[1439, 250000], [1439, 260000]]}, [91786, 6712]], ['last day endorsement', {'start': 2821, 'end': 3186, 'annual': 100000, 'endorsements': [[3185, 367523]]}, [733]]], [['single increase', {'start': 2447, 'end': 2812, 'annual': 190688, 'endorsements': [[2655, 312597]]}, [52438]], ['increase then decrease', {'start': 1314, 'end': 1679, 'annual': 268062, 'endorsements': [[1335, 344123], [1518, 58352]]}, [71685, -126052]], ['decrease then partial restore', {'start': 1117, 'end': 1482, 'annual': 100000, 'endorsements': [[1159, 40004], [1334, 61238]]}, [-53092, 8610]], ['leap-year term', {'start': 1273, 'end': 1639, 'annual': 241312, 'endorsements': [[1536, 193555]]}, [-13440]], ['six-month term', {'start': 49, 'end': 231, 'annual': 80756, 'endorsements': [[79, 411368], [219, 276361]]}, [276116, -8902]], ['endorsement on expiry rejected', {'start': 2167, 'end': 2532, 'annual': 216523, 'endorsements': [[2532, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 1680, 'end': 2045, 'annual': 258325, 'endorsements': [[1679, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 2653, 'end': 3018, 'annual': 115795, 'endorsements': [[2853, 200000], [2753, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 2438, 'end': 2803, 'annual': 251511, 'endorsements': [[2438, 112887]]}, [-138624]], ['same-day endorsements', {'start': 1751, 'end': 2116, 'annual': 210625, 'endorsements': [[1871, 250000], [1871, 260000]]}, [26430, 6712]], ['last day endorsement', {'start': 1049, 'end': 1414, 'annual': 100000, 'endorsements': [[1413, 290691]]}, [522]]], [['single increase', {'start': 567, 'end': 932, 'annual': 242069, 'endorsements': [[864, 340392]]}, [18318]], ['increase then decrease', {'start': 2519, 'end': 2884, 'annual': 179314, 'endorsements': [[2537, 319903], [2726, 81013]]}, [133656, -103410]], ['decrease then partial restore', {'start': 1092, 'end': 1457, 'annual': 100000, 'endorsements': [[1105, 40005], [1285, 62765]]}, [-57858, 10725]], ['leap-year term', {'start': 820, 'end': 1186, 'annual': 204385, 'endorsements': [[905, 292674]]}, [67785]], ['six-month term', {'start': 1400, 'end': 1582, 'annual': 108639, 'endorsements': [[1481, 441832], [1570, 418671]]}, [184904, -1527]], ['endorsement on expiry rejected', {'start': 936, 'end': 1301, 'annual': 206524, 'endorsements': [[1301, 200000]]}, 'invalid endorsement date'], ['endorsement before inception rejected', {'start': 983, 'end': 1348, 'annual': 294557, 'endorsements': [[982, 200000]]}, 'invalid endorsement date'], ['out of order rejected', {'start': 1953, 'end': 2318, 'annual': 262141, 'endorsements': [[2153, 200000], [2053, 250000]]}, 'invalid endorsement date'], ['inception-day endorsement', {'start': 2741, 'end': 3106, 'annual': 192566, 'endorsements': [[2741, 174344]]}, [-18222]], ['same-day endorsements', {'start': 114, 'end': 479, 'annual': 252584, 'endorsements': [[234, 250000], [234, 260000]]}, [-1734, 6712]], ['last day endorsement', {'start': 1695, 'end': 2060, 'annual': 100000, 'endorsements': [[2059, 111498]]}, [32]]]]
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
single increase[103670][103670]Passed
increase then decrease[156476, -116221][156476, -116221]Passed
decrease then partial restore[-48164, 8181][-48164, 8181]Passed
leap-year term[11810][11810]Passed
six-month term[51881, -1356][51881, -1356]Passed
endorsement on expiry rejectedinvalid endorsement dateinvalid endorsement datePassed
endorsement before inception rejectedinvalid endorsement dateinvalid endorsement datePassed
out of order rejectedinvalid endorsement dateinvalid endorsement datePassed
inception-day endorsement[228979][228979]Passed
same-day endorsements[37572, 6712][37572, 6712]Passed
last day endorsementinvalid endorsement date[426]Failed

SHA-256 / a8a99e5face0be5632c197aa0a2cc64067db6c8e67e1de180b768d8a3d4641d3

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 11 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 bounded teaching model of a stipulated toy rating contract. Amounts are integer cents and factors exact rationals; it makes no claim of conformance with any filed rating plan, bureau manual or jurisdiction. 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 2026-09-29T14:47:12.908028+00:00.

Case digest / 0ad89c3fab14beeb42f5c4e979076a17268d237df1eda0c1e2da235ad604423d