FAILURE MAP
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FA-5806 / Planar geometry / Open access

Ellipse area divided by pi · case 01

Only one semiaxis determines the area.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Only one semiaxis determines the area.

VERIFIED REPAIR

Apply the specified mathematical contract directly, preserving all terms and boundary cases: return a*b

Unsuccessful approach: Averaging axes first introduces an incorrect cross-section.

Case contract

Integer coordinates and lengths, with exact arithmetic except for indicated division results. Lengths are nonnegative. Rectangles are (xmin,ymin,xmax,ymax) with ordered bounds; coordinate vectors have matching dimensions. Ellipse area divided by pi. Exact operational definition: a*b

Why this case matters

Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Planar geometry results depend on the stated convention.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
import calendar
import statistics
import itertools
from fractions import Fraction
from datetime import date, datetime, timedelta, timezone
from decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR

N = 1
observations = []
def solve(a, b):
    return a*a
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: (3, 2)', solve(*(3, 2)), 6)
check('fixture 2: (2, 2)', solve(*(2, 2)), 4)
check('fixture 3: (0, 5)', solve(*(0, 5)), 0)
check('fixture 4: (4, 1)', solve(*(4, 1)), 4)
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
fixture 1: (3, 2)96Failed
fixture 2: (2, 2)44Passed
fixture 3: (0, 5)00Passed
fixture 4: (4, 1)164Failed

SHA-256 / 7f533ae6437ec47f7bb5befcd9179223db8999bf9fa2b2f24db77a946282373f

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
import calendar
import statistics
import itertools
from fractions import Fraction
from datetime import date, datetime, timedelta, timezone
from decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR

N = 1
observations = []
def solve(a, b):
    return (a+b)**2/4
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: (3, 2)', solve(*(3, 2)), 6)
check('fixture 2: (2, 2)', solve(*(2, 2)), 4)
check('fixture 3: (0, 5)', solve(*(0, 5)), 0)
check('fixture 4: (4, 1)', solve(*(4, 1)), 4)
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
fixture 1: (3, 2)6.256Failed
fixture 2: (2, 2)4.04Passed
fixture 3: (0, 5)6.250Failed
fixture 4: (4, 1)6.254Failed

SHA-256 / db1dc486a6f762827b461f76bf0d1276b707a9e18b5e66b1718cfa5aefd986ce

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import math
import calendar
import statistics
import itertools
from fractions import Fraction
from datetime import date, datetime, timedelta, timezone
from decimal import Decimal, ROUND_HALF_UP, ROUND_DOWN, ROUND_CEILING, ROUND_FLOOR

N = 1
observations = []
def solve(a, b):
    return a*b
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: (3, 2)', solve(*(3, 2)), 6)
check('fixture 2: (2, 2)', solve(*(2, 2)), 4)
check('fixture 3: (0, 5)', solve(*(0, 5)), 0)
check('fixture 4: (4, 1)', solve(*(4, 1)), 4)
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
fixture 1: (3, 2)66Passed
fixture 2: (2, 2)44Passed
fixture 3: (0, 5)00Passed
fixture 4: (4, 1)44Passed

SHA-256 / 2840b03c922ce30e93d6ca7d31962d2155cb22527b00962850f8b3f6fec8730e

Verification & scope

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 2026-09-29T14:37:53.835140+00:00.

Case digest / 4f0a8512afa4f6f86cb4831af16cd55cafed4417495e93555473c5e1b4ed7cbb