A Forced Answer Channel for Closed-Book Knowledge Base Construction at LM-KBC 2026

Yiqun Sun, Pengfei Wei, Lawrence B. Hsieh


Abstract
The AKBC 2026 shared task (Kalo et al., 2026) asks a system to complete the object set of a subject and a relation out of a language model’s parameters, with no retrieval, no training, and no more than 32B parameters. Our system drives one 29.6B backbone through three stages. Several elicitation channels per relation build a candidate pool, exhaustive one-token Yes/No probes verify whatever part of the answer space can be enumerated, and a per-relation decision layer emits the object set. The backbone writes a reasoning channel before its user-facing answer, so a probe prompt has to append the answer-channel header before its first generated token is a verdict. Forcing that channel also makes auxiliary generations cheap, which is what puts roughly 26k border probes inside the budget. Most decision constants are fitted on validation gold under a rule that displaces an incumbent only on a strict improvement of more than one row, and the fitting procedure itself is cross-validated, which cut one city gain from +0.070 to +0.020 before it was adopted. The system scores 0.6553 official macro-F1 against 0.6415 for a prompting baseline on the same backbone, and the gap is uneven: the machinery is worth +0.1662 on awards and costs 0.0204 on hasCapacity, where plain prompting wins. We also report the ceiling we could not move. Twenty-one method families have been fitted against hasCapacity and none of them beats a mass vote over the pool. Harvesting the model’s own reasoning traces raises pool coverage from 0.582 to 0.724 and converts none of it.
Anthology ID:
2026.akbc-1.30
Volume:
Proceedings of the 11th Workshop on Automated Knowledge Base Construction (AKBC 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Jan-Christoph Kalo, Ndapa Nakashole, Simon Razniewski, Fabian M. Suchanek, Andreas Vlachos, Andrew McCallum
Venues:
AKBC | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
427–433
Language:
URL:
https://aclanthology.org/2026.akbc-1.30/
DOI:
Bibkey:
Cite (ACL):
Yiqun Sun, Pengfei Wei, and Lawrence B. Hsieh. 2026. A Forced Answer Channel for Closed-Book Knowledge Base Construction at LM-KBC 2026. In Proceedings of the 11th Workshop on Automated Knowledge Base Construction (AKBC 2026), pages 427–433, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
A Forced Answer Channel for Closed-Book Knowledge Base Construction at LM-KBC 2026 (Sun et al., AKBC 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.akbc-1.30.pdf