MorphoFiltered-Gemini at MWE-2026 PARSEME 2.0 Subtask 1: Tackling LLM Overgeneration via Universal POS-based Constraints

Irina Moise, Sergiu Nisioi


Abstract
This paper describes MorphoFiltered-Gemini, a multilingual system submitted to the PARSEME 2.0 shared task on multiword expression (MWE) identification. The system relies on Google Gemini 2.0 Flash-Lite to generate MWE predictions using zero-shot and selectively applied few-shot prompting, without fine-tuning or language-specific resources. To reduce the tendency of large language models to over-generate MWEs, we introduce a lightweight morphological post-filter that removes unlikely constructions while preserving high-precision patterns.Rather than optimizing peak performance for individual languages, our approach prioritizes precision and cross-lingual robustness. As a result, the system exhibits stable behavior across 17 typologically diverse languages and achieves the highest Shannon evenness score among all submitted systems. The experimental results highlight a clear trade-off between recall-oriented LLM prompting strategies and precision-oriented filtering, and show that simple linguistic constraints can effectively improve the stability of LLM-based multilingual MWE identification systems.
Anthology ID:
2026.mwe-1.26
Volume:
Proceedings of the 22nd Workshop on Multiword Expressions (MWE 2026)
Month:
March
Year:
2026
Address:
Rabat, Marocco
Editors:
Atul Kr. Ojha, Verginica Barbu Mititelu, Mathieu Constant, Ivelina Stoyanova, A. Seza Doğruöz, Alexandre Rademaker
Venues:
MWE | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
196–202
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.mwe-1.26/
DOI:
Bibkey:
Cite (ACL):
Irina Moise and Sergiu Nisioi. 2026. MorphoFiltered-Gemini at MWE-2026 PARSEME 2.0 Subtask 1: Tackling LLM Overgeneration via Universal POS-based Constraints. In Proceedings of the 22nd Workshop on Multiword Expressions (MWE 2026), pages 196–202, Rabat, Marocco. Association for Computational Linguistics.
Cite (Informal):
MorphoFiltered-Gemini at MWE-2026 PARSEME 2.0 Subtask 1: Tackling LLM Overgeneration via Universal POS-based Constraints (Moise & Nisioi, MWE 2026)
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https://preview.aclanthology.org/ingest-eacl/2026.mwe-1.26.pdf