FA-100186 / Annotation span alignment / Open access

Touching spans are incorrectly reported as overlapping · case 01

Touching spans are incorrectly reported as overlapping.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The interval test uses inclusive endpoints for half-open spans.

THE FAILURE

The interval test uses inclusive endpoints for half-open spans.

Unsuccessful approach: Testing only strict start containment misses identical intervals with equal starts.

Case contract

Return true iff half-open intervals [a,b) and [c,d) share at least one position.

Why this case matters

A small offline annotation transformation keeps span coordinates explicit when text or token boundaries change.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(a, b, c, d):
    return a<=d and c<=b
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('touch at right edge', solve(0,N,N,N+2), False)
check('touch at left edge', solve(N,N+2,0,N), False)
check('positive overlap', solve(0,N+1,N,N+3), True)
check('disjoint', solve(0,2,4,6), False)
check('contained', solve(0,8,2,3), True)
check('identical', solve(N,N+1,N,N+1), True)
check('empty first', solve(2,2,1,3), 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
touch at right edge	`True`	`False`	Failed
touch at left edge	`True`	`False`	Failed
positive overlap	`True`	`True`	Passed
disjoint	`False`	`False`	Passed
contained	`True`	`True`	Passed
identical	`True`	`True`	Passed
empty first	`True`	`False`	Failed

SHA-256 / 8fead298434849ae57f71be57812124001a5f79e3d973e35c4e90abf74cee11d

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(a, b, c, d):
    return a<c< b or c<a<d
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('touch at right edge', solve(0,N,N,N+2), False)
check('touch at left edge', solve(N,N+2,0,N), False)
check('positive overlap', solve(0,N+1,N,N+3), True)
check('disjoint', solve(0,2,4,6), False)
check('contained', solve(0,8,2,3), True)
check('identical', solve(N,N+1,N,N+1), True)
check('empty first', solve(2,2,1,3), 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
touch at right edge	`False`	`False`	Passed
touch at left edge	`False`	`False`	Passed
positive overlap	`True`	`True`	Passed
disjoint	`False`	`False`	Passed
contained	`True`	`True`	Passed
identical	`False`	`True`	Failed
empty first	`True`	`False`	Failed

SHA-256 / 7908537c8653d708ff7aeac16aa2d447ccee0fd40b31d6afc1a464f280ef6a97

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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

Contracts use integer offsets, explicit edits, and supplied token boundaries; they do not define a tokenizer or production annotation format. 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 2026-09-30T16:48:32.646646+00:00.

Case digest / 311f066bf555621876d9824405c7a192cfbb98ff97df3eacfa922e9b79a75c2e