Supervision versus Demonstration-Based In-Context Learning for Multiword Expression Classification

Sercan Karakaş, Yusuf Şimşek


Abstract
Turkish idiomatic light verb constructions (LVCs) are challenging for multiword expression processing because they often share the same surface form as fully literal verb–object combinations while functioning as a single, partially idiomatic predicate. We frame Turkish LVC detection as a binary classification task (literal meaning vs. idiomatic meaning) and evaluate on a manually created controlled set (N=147) with matched negatives: out-of-domain random sentences and in-domain literal controls (NLVC), alongside LVC positives. We compare a supervised Turkish encoder baseline (BERTurk with a classifier head) to three instruction-tuned LLMs from different families under zero-shot, one-shot, and few-shot prompting, and analyze how demonstrations shift error profiles. In zero-shot, LLMs perform well on negatives but show very low LVC recall. One-shot prompting sharply improves LVC detection but can induce strong, model-specific biases (over- vs. under-predicting LVC). A richer few-shot prompt improves calibration and yields robust overall performance for GPT-OSS-20B and Qwen 2.5-14B. Overall, the results highlight substantial prompt sensitivity in Turkish metalinguistic classification: the supervised baseline remains competitive, while prompted LLMs can match or exceed it on LVCs with carefully constructed demonstrations. We release code, prompts, and evaluation materials to support reproducibility.
Anthology ID:
2026.acl-srw.71
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Santosh T.Y.S.S., Juan Diego Rodriguez, Ona de Gibert
Venue:
ACL
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Publisher:
Association for Computational Linguistics
Note:
Pages:
800–815
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URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-srw.71/
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Bibkey:
Cite (ACL):
Sercan Karakaş and Yusuf Şimşek. 2026. Supervision versus Demonstration-Based In-Context Learning for Multiword Expression Classification. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026), pages 800–815, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Supervision versus Demonstration-Based In-Context Learning for Multiword Expression Classification (Karakaş & Şimşek, ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-srw.71.pdf