Tangut is an extinct language whose script does not explicitly mark word boundaries. We present the first systematic study of Tangut word segmentation using 2,750 expert-annotated segments (31,893 tokens), traditional lexicons, and unlabeled text. Our framework combines a reliability-calibrated lexicon-lattice representation, explicit distributional statistics, and a lightweight character encoder pretrained with MLM. In within-source five-fold cross-validation, the model integrating TangutEncoder, CRF, and external features obtains the numerically highest main-system mean F1 of 0.911 and substantially improves recall beyond the labeled training vocabulary. We further evaluate document-level transfer on 479 segments (4081 tokens) from five works absent from the annotated training corpus. You can access our project at https://github.com/jiangli-va/TangutSeg.

翻译：暂无翻译