FA-5851 / Planar geometry / Open access

Counterclockwise quarter turn · case 01

The rotation direction is reversed.

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

ROOT CAUSE

The rotation direction is reversed.

VERIFIED REPAIR

Apply the specified mathematical contract directly, preserving all terms and boundary cases: return (-point[1],point[0])

Unsuccessful approach: Negating both coordinates rotates by a half turn.

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. Counterclockwise quarter turn. Exact operational definition: (-point[1],point[0])

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(point):
    return (point[1],-point[0])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: ((2, 3),)', solve(*((2, 3),)), (-3, 2))
check('fixture 2: ((0, 1),)', solve(*((0, 1),)), (-1, 0))
check('fixture 3: ((-2, 0),)', solve(*((-2, 0),)), (0, -2))
check('fixture 4: ((0, 0),)', solve(*((0, 0),)), (0, 0))
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
fixture 1: ((2, 3),)	`[3, -2]`	`[-3, 2]`	Failed
fixture 2: ((0, 1),)	`[1, 0]`	`[-1, 0]`	Failed
fixture 3: ((-2, 0),)	`[0, 2]`	`[0, -2]`	Failed
fixture 4: ((0, 0),)	`[0, 0]`	`[0, 0]`	Passed

SHA-256 / b2d8406cd597888552a541cb24ad3ed4ed225f8efd0232056dc27fc40767989c

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(point):
    return (-point[0],-point[1])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: ((2, 3),)', solve(*((2, 3),)), (-3, 2))
check('fixture 2: ((0, 1),)', solve(*((0, 1),)), (-1, 0))
check('fixture 3: ((-2, 0),)', solve(*((-2, 0),)), (0, -2))
check('fixture 4: ((0, 0),)', solve(*((0, 0),)), (0, 0))
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
fixture 1: ((2, 3),)	`[-2, -3]`	`[-3, 2]`	Failed
fixture 2: ((0, 1),)	`[0, -1]`	`[-1, 0]`	Failed
fixture 3: ((-2, 0),)	`[2, 0]`	`[0, -2]`	Failed
fixture 4: ((0, 0),)	`[0, 0]`	`[0, 0]`	Passed

SHA-256 / 28c45a2125de0910fec066d110af8ec894c6e32f8e5fd4fdb710eca7d484a038

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(point):
    return (-point[1],point[0])
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1: ((2, 3),)', solve(*((2, 3),)), (-3, 2))
check('fixture 2: ((0, 1),)', solve(*((0, 1),)), (-1, 0))
check('fixture 3: ((-2, 0),)', solve(*((-2, 0),)), (0, -2))
check('fixture 4: ((0, 0),)', solve(*((0, 0),)), (0, 0))
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
fixture 1: ((2, 3),)	`[-3, 2]`	`[-3, 2]`	Passed
fixture 2: ((0, 1),)	`[-1, 0]`	`[-1, 0]`	Passed
fixture 3: ((-2, 0),)	`[0, -2]`	`[0, -2]`	Passed
fixture 4: ((0, 0),)	`[0, 0]`	`[0, 0]`	Passed

SHA-256 / 6c66dc6b65cf1f80942084cf9c8eaa8902130c378c30fcf85f0768037b84655d

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 2026-09-29T14:37:54.482478+00:00.

Case digest / 6705d28cf33d2352bc2f488811748dd6189d9a0fd4b6e33334a7007f1e24123a