FA-4686 / Multiset accounting / Open access
Counter unary plus filters strictly positive · case 01
The operation returns a result or retained state that violates this contract: Unary counter normalization retains strictly positive counts without changing them.
ROOT CAUSE
Returning the raw mapping leaves zero and negative entries present.
VERIFIED REPAIR
Unary counter normalization retains strictly positive counts without changing them.
Unsuccessful approach: An inclusive zero boundary retains zero entries.
Case contract
Unary counter normalization retains strictly positive counts without changing them. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.
Why this case matters
A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
from collections import Counter, ChainMap, deque
import heapq
N = 1
observations = []
def solve(x, y=None):
return dict(x)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('mixed signs', solve({'a': 2, 'b': 0, 'c': -1}), {'a': 2})
check('zero', solve({'a': 0}), {})
check('negative', solve({'a': -2}), {})
check('empty', 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 |
|---|---|---|---|
| mixed signs | {'a': 2, 'b': 0, 'c': -1} | {'a': 2} | Failed |
| zero | {'a': 0} | {} | Failed |
| negative | {'a': -2} | {} | Failed |
| empty | {} | {} | Passed |
SHA-256 / 7092f2abfaf112ae5c059b3eef316c97441e27a6b1eff5790c67a54ec39b8acf
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
from collections import Counter, ChainMap, deque
import heapq
N = 1
observations = []
def solve(x, y=None):
return {k:v for k,v in x.items() if v>=0}
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('mixed signs', solve({'a': 2, 'b': 0, 'c': -1}), {'a': 2})
check('zero', solve({'a': 0}), {})
check('negative', solve({'a': -2}), {})
check('empty', 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 |
|---|---|---|---|
| mixed signs | {'a': 2, 'b': 0} | {'a': 2} | Failed |
| zero | {'a': 0} | {} | Failed |
| negative | {} | {} | Passed |
| empty | {} | {} | Passed |
SHA-256 / 60d4b8f1221681eae4fde78861e3e3d2ddf0143e07f48c157d71581074744b8f
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
from collections import Counter, ChainMap, deque
import heapq
N = 1
observations = []
def solve(x, y=None):
return dict(+Counter(x))
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('mixed signs', solve({'a': 2, 'b': 0, 'c': -1}), {'a': 2})
check('zero', solve({'a': 0}), {})
check('negative', solve({'a': -2}), {})
check('empty', 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 |
|---|---|---|---|
| mixed signs | {'a': 2} | {'a': 2} | Passed |
| zero | {} | {} | Passed |
| negative | {} | {} | Passed |
| empty | {} | {} | Passed |
SHA-256 / 7694401d1bcf209cbfa4d5362cfe1876ca7470f19a367e05c6c138e41a3b8587
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 2026-09-29T14:37:41.742655+00:00.
Case digest / 2745c5cc9f7c3a5beb40e8a6681f4e762063418271f2cf33b62832c406f4a01d