FA-3126 / Regular expressions / Open access

Overlapping motif matches are skipped · case 01

Overlapping motif matches are skipped.

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: Return every start index of aba, including overlaps.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Return every start index of aba, including overlaps.

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

Case contract

Return every start index of aba, including overlaps.

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 [m.start() for m in re.finditer('aba',x)]
    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('ababa'), [0, 2])
check('boundary 2', solve('abaaba'), [0, 3])
check('boundary 3', solve('xaba'), [1])
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	`[0]`	`[0, 2]`	Failed
boundary 2	`[0, 3]`	`[0, 3]`	Passed
boundary 3	`[1]`	`[1]`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / 01d7998cca2f3a9046de05f7ba3fd27d0b538490f1b66e53aa47992a3dd4b21d

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 [x.find('aba')] if 'aba' in x else []
    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('ababa'), [0, 2])
check('boundary 2', solve('abaaba'), [0, 3])
check('boundary 3', solve('xaba'), [1])
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	`[0]`	`[0, 2]`	Failed
boundary 2	`[0]`	`[0, 3]`	Failed
boundary 3	`[1]`	`[1]`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / c1e8e3a4452e576e71258321a9ecfd3f7e7eb14c556449e88351996d305ae23f

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 [m.start() for m in re.finditer('(?=aba)',x)]
    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('ababa'), [0, 2])
check('boundary 2', solve('abaaba'), [0, 3])
check('boundary 3', solve('xaba'), [1])
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	`[0, 2]`	`[0, 2]`	Passed
boundary 2	`[0, 3]`	`[0, 3]`	Passed
boundary 3	`[1]`	`[1]`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / dcaa074a1a48142ecc9026872d2fe89915702dface7d3ed0837d8464806f730d

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 2026-09-29T14:37:21.683688+00:00.

Case digest / c80c59f4b7e190d801352d3ab72c7aad819717618cd469d156db4aff9468262d