FA-100086 / Preference pair construction / Open access

Preference pairs: only adjacent candidates are paired · case 01

only adjacent candidates are paired.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Adjacent list traversal omits valid preference comparisons between non-neighbor candidates.

THE FAILURE

Adjacent list traversal omits valid preference comparisons between non-neighbor candidates.

Unsuccessful approach: Extending the traversal to skip one candidate finds distant pairs but omits adjacent comparisons.

Case contract

Candidates are [id,score]. Return every unordered pair [higher_id,lower_id] once; tied scores are skipped. Order follows input index pairs.

Why this case matters

A small deterministic preference-data transform makes pair semantics inspectable without a training framework.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(candidates):
    return [[candidates[i][0],candidates[i+1][0]] for i in range(len(candidates)-1) if candidates[i][1]>candidates[i+1][1]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
a='a'+str(N); b='b'+str(N); c='c'+str(N)
check('nonadjacent pair',solve([[a,3],[b,1],[c,2]]),[[a,b],[a,c],[c,b]])
check('two candidates',solve([[a,1],[b,0]]),[[a,b]])
check('tie skipped',solve([[a,1],[b,1]]),[])
check('singleton',solve([[a,1]]),[])
check('empty',solve([]),[])
check('all descending',solve([[a,3],[b,2],[c,1]]),[[a,b],[a,c],[b,c]])
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
nonadjacent pair	`[['a1', 'b1']]`	`[['a1', 'b1'], ['a1', 'c1'], ['c1', 'b1']]`	Failed
two candidates	`[['a1', 'b1']]`	`[['a1', 'b1']]`	Passed
tie skipped	`[]`	`[]`	Passed
singleton	`[]`	`[]`	Passed
empty	`[]`	`[]`	Passed
all descending	`[['a1', 'b1'], ['b1', 'c1']]`	`[['a1', 'b1'], ['a1', 'c1'], ['b1', 'c1']]`	Failed

SHA-256 / 838d5f37d90131c0028f8d18c67c3195740e424c0b4f87c31740741a1f84898f

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(candidates):
    return [[a[0],b[0]] if a[1]>b[1] else [b[0],a[0]] for i,a in enumerate(candidates) for b in candidates[i+2:] if a[1]!=b[1]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
a='a'+str(N); b='b'+str(N); c='c'+str(N)
check('nonadjacent pair',solve([[a,3],[b,1],[c,2]]),[[a,b],[a,c],[c,b]])
check('two candidates',solve([[a,1],[b,0]]),[[a,b]])
check('tie skipped',solve([[a,1],[b,1]]),[])
check('singleton',solve([[a,1]]),[])
check('empty',solve([]),[])
check('all descending',solve([[a,3],[b,2],[c,1]]),[[a,b],[a,c],[b,c]])
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
nonadjacent pair	`[['a1', 'c1']]`	`[['a1', 'b1'], ['a1', 'c1'], ['c1', 'b1']]`	Failed
two candidates	`[]`	`[['a1', 'b1']]`	Failed
tie skipped	`[]`	`[]`	Passed
singleton	`[]`	`[]`	Passed
empty	`[]`	`[]`	Passed
all descending	`[['a1', 'c1']]`	`[['a1', 'b1'], ['a1', 'c1'], ['b1', 'c1']]`	Failed

SHA-256 / c74636e4aaa404da24912836eeaffd11c3756b715187f82f7100adac07d5ccf1

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

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Verification & scope

These are explicit toy record contracts; they do not claim compatibility with a trainer or improved model behavior. 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 2026-09-30T16:48:31.716660+00:00.

Case digest / 143e7852d13194b0ed62bda22d6f12b04c50b0aeb568b71e48c63c692f498f1c