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FA-62956 / Insurance premium rating / Open access

Increased limits factor layer pricing: Excess layer subtracts the wrong lower factor · case 01

Excess layers are charged the full ground-up premium.

Verified by executionVariant 1 · 10 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The lower ILF at the attachment point is not subtracted.

THE FAILURE

The lower ILF at the attachment point is not subtracted.

Unsuccessful approach: Subtracting the ILF of the layer width uses the wrong reference point.

Case contract

Input basic (premium at basic limit), ilf table [[limit, factor*1000]] ascending, attachment, layer_limit. ILF(0)=0 and ILF is linear between tabulated points (including from 0 to the basic limit); limits above the table are unrated. Layer premium = floor(basic*(ILF(att+lim)-ILF(att))/1000+1/2). layer_limit<=0 or attachment<0 -> 'invalid'.

Why this case matters

Premium rating engines apply ordered tabular rules where one misplaced boundary or step silently misprices policies.

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):
    if x['layer_limit']<=0 or x['attachment']<0: return 'invalid'
    tab=[[0,0]]+x['ilf']
    def ilf(L):
        if L>tab[-1][0]: return None
        for (l0,f0),(l1,f1) in zip(tab,tab[1:]):
            if l0<=L<=l1:
                return f0+Fraction(f1-f0)*(L-l0)/(l1-l0)
    top=ilf(x['attachment']+x['layer_limit']); bot=ilf(x['attachment'])
    if top is None or bot is None: return 'unrated'
    return math.floor(x['basic']*top/1000+Fraction(1,2))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['primary basic limit', {'basic': 43747, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 100000}, 43747], ['primary interpolated limit', {'basic': 104803, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 375000}, 150130], ['excess layer 500 xs 500', {'basic': 91047, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 500000, 'layer_limit': 500000}, 22944], ['excess layer interpolated', {'basic': 74589, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 130000, 'layer_limit': 650000}, 47298], ['layer up to maximum', {'basic': 60555, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 1000000, 'layer_limit': 1000000}, 14897], ['layer beyond maximum', {'basic': 100477, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 110006, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 60000}, 66004], ['zero width layer rejected', {'basic': 64657, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 109079, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 61004, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 250000, 'layer_limit': 750000}, 30319]], [['primary basic limit', {'basic': 83688, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 100000}, 83688], ['primary interpolated limit', {'basic': 62537, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 400000}, 91554], ['excess layer 500 xs 500', {'basic': 72974, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 500000, 'layer_limit': 500000}, 18535], ['excess layer interpolated', {'basic': 96963, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 180000, 'layer_limit': 310000}, 36820], ['layer up to maximum', {'basic': 51640, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 1000000, 'layer_limit': 1000000}, 12497], ['layer beyond maximum', {'basic': 96337, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 80166, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 25000}, 20042], ['zero width layer rejected', {'basic': 40984, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 99315, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 88492, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 250000, 'layer_limit': 750000}, 43715]], [['primary basic limit', {'basic': 103077, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 100000}, 103077], ['primary interpolated limit', {'basic': 75700, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 410000}, 112066], ['excess layer 500 xs 500', {'basic': 91514, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 500000, 'layer_limit': 500000}, 23428], ['excess layer interpolated', {'basic': 116014, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 180000, 'layer_limit': 330000}, 45723], ['layer up to maximum', {'basic': 104427, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 1000000, 'layer_limit': 1000000}, 24854], ['layer beyond maximum', {'basic': 94873, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 82268, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 75000}, 61701], ['zero width layer rejected', {'basic': 98050, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 105611, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 93132, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 250000, 'layer_limit': 750000}, 45728]], [['primary basic limit', {'basic': 99090, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 100000}, 99090], ['primary interpolated limit', {'basic': 69051, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 470000}, 106504], ['excess layer 500 xs 500', {'basic': 103830, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 500000, 'layer_limit': 500000}, 26788], ['excess layer interpolated', {'basic': 41042, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 130000, 'layer_limit': 300000}, 17960], ['layer up to maximum', {'basic': 69534, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 1000000, 'layer_limit': 1000000}, 16271], ['layer beyond maximum', {'basic': 116762, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 119876, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 60000}, 71926], ['zero width layer rejected', {'basic': 54051, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 49440, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 49001, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 250000, 'layer_limit': 750000}, 23912]], [['primary basic limit', {'basic': 88505, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 100000}, 88505], ['primary interpolated limit', {'basic': 109050, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 315000}, 153597], ['excess layer 500 xs 500', {'basic': 53196, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 500000, 'layer_limit': 500000}, 13831], ['excess layer interpolated', {'basic': 106149, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 230000, 'layer_limit': 370000}, 34357], ['layer up to maximum', {'basic': 43019, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 1000000, 'layer_limit': 1000000}, 9894], ['layer beyond maximum', {'basic': 50180, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 81006, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 85000}, 68855], ['zero width layer rejected', {'basic': 54442, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 105893, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 110451, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 250000, 'layer_limit': 750000}, 53569]]]
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
primary basic limit4374743747Passed
primary interpolated limit150130150130Passed
excess layer 500 xs 50016452222944Failed
excess layer interpolated12651247298Failed
layer up to maximum12431914897Failed
layer beyond maximumunratedunratedPassed
limit below basic6600466004Passed
zero width layer rejectedinvalidinvalidPassed
negative attachment rejectedinvalidinvalidPassed
high excess layer11023430319Failed

SHA-256 / 63328e64b798e8861da5a6e80af9b8481f72086238e48e148453850f0ab958a6

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):
    if x['layer_limit']<=0 or x['attachment']<0: return 'invalid'
    tab=[[0,0]]+x['ilf']
    def ilf(L):
        if L>tab[-1][0]: return None
        for (l0,f0),(l1,f1) in zip(tab,tab[1:]):
            if l0<=L<=l1:
                return f0+Fraction(f1-f0)*(L-l0)/(l1-l0)
    top=ilf(x['attachment']+x['layer_limit']); bot=ilf(x['attachment'])
    if top is None or bot is None: return 'unrated'
    return math.floor(x['basic']*(top-ilf(x['layer_limit']))/1000+Fraction(1,2))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['primary basic limit', {'basic': 43747, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 100000}, 43747], ['primary interpolated limit', {'basic': 104803, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 375000}, 150130], ['excess layer 500 xs 500', {'basic': 91047, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 500000, 'layer_limit': 500000}, 22944], ['excess layer interpolated', {'basic': 74589, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 130000, 'layer_limit': 650000}, 47298], ['layer up to maximum', {'basic': 60555, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 1000000, 'layer_limit': 1000000}, 14897], ['layer beyond maximum', {'basic': 100477, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 110006, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 0, 'layer_limit': 60000}, 66004], ['zero width layer rejected', {'basic': 64657, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 109079, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 61004, 'ilf': [[100000, 1000], [250000, 1310], [500000, 1555], [1000000, 1807], [2000000, 2053]], 'attachment': 250000, 'layer_limit': 750000}, 30319]], [['primary basic limit', {'basic': 83688, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 100000}, 83688], ['primary interpolated limit', {'basic': 62537, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 400000}, 91554], ['excess layer 500 xs 500', {'basic': 72974, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 500000, 'layer_limit': 500000}, 18535], ['excess layer interpolated', {'basic': 96963, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 180000, 'layer_limit': 310000}, 36820], ['layer up to maximum', {'basic': 51640, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 1000000, 'layer_limit': 1000000}, 12497], ['layer beyond maximum', {'basic': 96337, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 80166, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 0, 'layer_limit': 25000}, 20042], ['zero width layer rejected', {'basic': 40984, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 99315, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 88492, 'ilf': [[100000, 1000], [250000, 1320], [500000, 1560], [1000000, 1814], [2000000, 2056]], 'attachment': 250000, 'layer_limit': 750000}, 43715]], [['primary basic limit', {'basic': 103077, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 100000}, 103077], ['primary interpolated limit', {'basic': 75700, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 410000}, 112066], ['excess layer 500 xs 500', {'basic': 91514, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 500000, 'layer_limit': 500000}, 23428], ['excess layer interpolated', {'basic': 116014, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 180000, 'layer_limit': 330000}, 45723], ['layer up to maximum', {'basic': 104427, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 1000000, 'layer_limit': 1000000}, 24854], ['layer beyond maximum', {'basic': 94873, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 82268, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 0, 'layer_limit': 75000}, 61701], ['zero width layer rejected', {'basic': 98050, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 105611, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 93132, 'ilf': [[100000, 1000], [250000, 1330], [500000, 1565], [1000000, 1821], [2000000, 2059]], 'attachment': 250000, 'layer_limit': 750000}, 45728]], [['primary basic limit', {'basic': 99090, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 100000}, 99090], ['primary interpolated limit', {'basic': 69051, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 470000}, 106504], ['excess layer 500 xs 500', {'basic': 103830, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 500000, 'layer_limit': 500000}, 26788], ['excess layer interpolated', {'basic': 41042, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 130000, 'layer_limit': 300000}, 17960], ['layer up to maximum', {'basic': 69534, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 1000000, 'layer_limit': 1000000}, 16271], ['layer beyond maximum', {'basic': 116762, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 119876, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 0, 'layer_limit': 60000}, 71926], ['zero width layer rejected', {'basic': 54051, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 49440, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 49001, 'ilf': [[100000, 1000], [250000, 1340], [500000, 1570], [1000000, 1828], [2000000, 2062]], 'attachment': 250000, 'layer_limit': 750000}, 23912]], [['primary basic limit', {'basic': 88505, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 100000}, 88505], ['primary interpolated limit', {'basic': 109050, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 315000}, 153597], ['excess layer 500 xs 500', {'basic': 53196, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 500000, 'layer_limit': 500000}, 13831], ['excess layer interpolated', {'basic': 106149, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 230000, 'layer_limit': 370000}, 34357], ['layer up to maximum', {'basic': 43019, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 1000000, 'layer_limit': 1000000}, 9894], ['layer beyond maximum', {'basic': 50180, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 1500000, 'layer_limit': 1000000}, 'unrated'], ['limit below basic', {'basic': 81006, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 0, 'layer_limit': 85000}, 68855], ['zero width layer rejected', {'basic': 54442, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 250000, 'layer_limit': 0}, 'invalid'], ['negative attachment rejected', {'basic': 105893, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': -50000, 'layer_limit': 100000}, 'invalid'], ['high excess layer', {'basic': 110451, 'ilf': [[100000, 1000], [250000, 1350], [500000, 1575], [1000000, 1835], [2000000, 2065]], 'attachment': 250000, 'layer_limit': 750000}, 53569]]]
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
primary basic limit043747Failed
primary interpolated limit0150130Failed
excess layer 500 xs 5002294422944Passed
excess layer interpolated488747298Failed
layer up to maximum1489714897Passed
layer beyond maximumunratedunratedPassed
limit below basic066004Failed
zero width layer rejectedinvalidinvalidPassed
negative attachment rejectedinvalidinvalidPassed
high excess layer768730319Failed

SHA-256 / 12079003a6a3c53493c294f7ebb0a80a8d9854310dc7da115c25a1522bcc35af

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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 2026-09-29T14:47:09.668562+00:00.

Case digest / 2ff6f45346d04d8907dab9eb58a5017c530fb3c0478984fc3978d014e67e80a7