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Alphabetic filtering admits combining letter numbers · case 01

Alphabetic filtering admits combining letter numbers.

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

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Keep only Unicode characters whose general category starts with L.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Keep only Unicode characters whose general category starts with L.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Keep only Unicode characters whose general category starts with L.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return ''.join(c for c in x if c.isalnum())
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('A1Ⅳ'), 'A')
check('boundary 2', solve('中é'), '中é')
check('boundary 3', solve('á'), 'a')
check('boundary 4', solve(''), '')
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
boundary 1	`A1Ⅳ`	`A`	Failed
boundary 2	`中é`	`中é`	Passed
boundary 3	`a`	`a`	Passed
boundary 4			Passed

SHA-256 / ad14604724c131356bdaee3e010541d10d5d5e03eda4b882811242182a7c9b8e

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return ''.join(c for c in x if c.isalpha() or c.isnumeric())
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('A1Ⅳ'), 'A')
check('boundary 2', solve('中é'), '中é')
check('boundary 3', solve('á'), 'a')
check('boundary 4', solve(''), '')
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
boundary 1	`A1Ⅳ`	`A`	Failed
boundary 2	`中é`	`中é`	Passed
boundary 3	`a`	`a`	Passed
boundary 4			Passed

SHA-256 / 84151a5ced90b3d1c295015b2610ca24a08cd506365b3ed5c01a0505e5b0ef90

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return ''.join(c for c in x if unicodedata.category(c).startswith('L'))
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('A1Ⅳ'), 'A')
check('boundary 2', solve('中é'), '中é')
check('boundary 3', solve('á'), 'a')
check('boundary 4', solve(''), '')
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
boundary 1	`A`	`A`	Passed
boundary 2	`中é`	`中é`	Passed
boundary 3	`a`	`a`	Passed
boundary 4			Passed

SHA-256 / 05e81c60e0b77c006124214acb7aac28a7b59af3dcfd40f2e0daacd2c5f475fe

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 2026-09-29T14:37:18.853974+00:00.

Case digest / 8403b21c9b52283341149cc81879680b9c447b533b8c95d5bce1d457838c61cd