FA-4306 / Collection algebra / Open access

Disjointness ignores order · case 01

The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.

Verified by executionVariant 1 · 5 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Sequence inequality is mistaken for absence of shared members.

THE FAILURE

Sequence inequality is mistaken for absence of shared members.

Unsuccessful approach: Zipping checks only aligned positions and misses cross-position overlaps.

Case contract

Return true exactly when the operands share no value. 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

N = 1
observations = []
def solve(x, y=None):
    return x != y
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('both empty', solve([], []), True)
check('empty right operand', solve(['a'], []), True)
check('empty left operand', solve([], ['b']), True)
check('overlap and multiplicity', solve(['b', 'a', 'b'], ['b', 'c', 'c']), False)
check('overlap at different positions', solve(['a','b'], ['b','c']), False)
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
both empty	`False`	`True`	Failed
empty right operand	`True`	`True`	Passed
empty left operand	`True`	`True`	Passed
overlap and multiplicity	`True`	`False`	Failed
overlap at different positions	`True`	`False`	Failed

SHA-256 / 52ed7ff7e76add53df27fc2909abec2d2167535883ce641ca2b8e37a4409e00c

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x, y=None):
    return all(a != b for a,b in zip(x,y))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('both empty', solve([], []), True)
check('empty right operand', solve(['a'], []), True)
check('empty left operand', solve([], ['b']), True)
check('overlap and multiplicity', solve(['b', 'a', 'b'], ['b', 'c', 'c']), False)
check('overlap at different positions', solve(['a','b'], ['b','c']), False)
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
both empty	`True`	`True`	Passed
empty right operand	`True`	`True`	Passed
empty left operand	`True`	`True`	Passed
overlap and multiplicity	`False`	`False`	Passed
overlap at different positions	`True`	`False`	Failed

SHA-256 / 530300ec44f457746e16678bf775e1aa760fe74e087f2ce08b7f1d35e24b2419

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 5 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:37:37.824910+00:00.

Case digest / a53f67a3a3a49118aa5e04063c1db4c757d3d1bc9ea0c0376a171e61566383de