TurCOMET: A Morphologically-Aware Evaluation System for Document-Level Turkish-English Machine Translation

Atahan Uz, Hüseyin Emir Akdağ, Susan Üsküdarlı


Abstract
We introduce TurCOMET, the first Turkish-specific augmentation of COMET for evaluating translations between Turkish and English. By extending xCOMET-XL with Turkish morphological features and training it on additional Turkish-English data via an additive bottleneck layer, TurCOMET resolves neural evaluation failures caused by sub-word over-segmentation. To validate our metric, we introduce TurkDoc-MT, a meticulously curated Turkish-English document-level aligned dataset of 1,322 instances spanning seven domains. Meta-evaluation demonstrates that TurCOMET significantly outperforms the off-the-shelf baseline, yielding absolute Kendall’s τ correlation gains of +0.113 (system-level) and +0.024 (segment-level), with the largest gains in the TR→EN direction. All models, datasets, code, and annotations are publicly released for the benefit of Turkish natural language processing and benchmarking any translation system.
Anthology ID:
2026.emnlp-main.2672
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
60806–60826
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2672/
DOI:
Bibkey:
Cite (ACL):
Atahan Uz, Hüseyin Emir Akdağ, and Susan Üsküdarlı. 2026. TurCOMET: A Morphologically-Aware Evaluation System for Document-Level Turkish-English Machine Translation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 60806–60826, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TurCOMET: A Morphologically-Aware Evaluation System for Document-Level Turkish-English Machine Translation (Uz et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2672.pdf