FA-100051 / Preference pair construction / Open access

Preference pairs: ineligible responses become pair endpoints · case 01

ineligible responses become pair endpoints.

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

ROOT CAUSE

Preference is evaluated before candidate eligibility is applied.

THE FAILURE

Preference is evaluated before candidate eligibility is applied.

Unsuccessful approach: Filtering only the chosen endpoint can leave a rejected endpoint that is forbidden.

Case contract

Candidates are [id,score,eligible]. Select the highest and lowest scored eligible candidates; return [best_id,worst_id], or None with fewer than two eligible candidates.

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 [max(candidates,key=lambda x:x[1])[0],min(candidates,key=lambda x:x[1])[0]] if len(candidates)>1 else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
a='a'+str(N); b='b'+str(N); x='x'+str(N)
check('excluded maximum',solve([[a,N,True],[x,N+3,False],[b,0,True]]),[a,b])
check('excluded minimum',solve([[a,N,True],[x,-N,False],[b,0,True]]),[a,b])
check('one eligible',solve([[a,N,True],[x,0,False]]),None)
check('none eligible',solve([[a,N,False],[b,0,False]]),None)
check('empty',solve([]),None)
check('two eligible',solve([[a,2*N,True],[b,N,True]]),[a,b])
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
excluded maximum	`['x1', 'b1']`	`['a1', 'b1']`	Failed
excluded minimum	`['a1', 'x1']`	`['a1', 'b1']`	Failed
one eligible	`['a1', 'x1']`	`None`	Failed
none eligible	`['a1', 'b1']`	`None`	Failed
empty	`None`	`None`	Passed
two eligible	`['a1', 'b1']`	`['a1', 'b1']`	Passed

SHA-256 / 8f1becb91e686f358aeca0cb11f0b83e4bee0eb5aacddf23d1a0500cd010bb96

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(candidates):
    ok=[c for c in candidates if c[2]]
    return [max(ok,key=lambda x:x[1])[0],min(candidates,key=lambda x:x[1])[0]] if len(ok)>1 else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
a='a'+str(N); b='b'+str(N); x='x'+str(N)
check('excluded maximum',solve([[a,N,True],[x,N+3,False],[b,0,True]]),[a,b])
check('excluded minimum',solve([[a,N,True],[x,-N,False],[b,0,True]]),[a,b])
check('one eligible',solve([[a,N,True],[x,0,False]]),None)
check('none eligible',solve([[a,N,False],[b,0,False]]),None)
check('empty',solve([]),None)
check('two eligible',solve([[a,2*N,True],[b,N,True]]),[a,b])
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
excluded maximum	`['a1', 'b1']`	`['a1', 'b1']`	Passed
excluded minimum	`['a1', 'x1']`	`['a1', 'b1']`	Failed
one eligible	`None`	`None`	Passed
none eligible	`None`	`None`	Passed
empty	`None`	`None`	Passed
two eligible	`['a1', 'b1']`	`['a1', 'b1']`	Passed

SHA-256 / 7d9a75b0fede1a5b7f744ebaf9b1e018ce4dc5274fc29592b4d50e81cffdb2c7

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.

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

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 2026-09-30T16:48:31.262650+00:00.

Case digest / 514a6985016bf1c69f5d05c3cf16a40839f82a8e990e2cf6388d4d09176cbbbf