A Learnable Skill Combination Strategy for Multi-task Learning in Natural Language Understanding
Paper · 2026 · Zhe Yang, Yi Huang, Yaqin Chen et al.
Summary
Labeled data for domain-specific natural language understanding is scarce. Multi-task learning can help, but current sparse designs have weaknesses. Skill-Net needs task-to-skill assignments chosen by hand. MMoE uses a fixed top-k routing that can overload some experts. The authors replace each feed-forward layer of a BERT-style encoder with a cluster of FFN "skill" modules. Tasks and skills each get their own learnable embeddings. A projected dot product followed by a sigmoid scores how relevant each skill is to each task. A smooth surrogate of a hard threshold turns these scores into near-binary on/off choices, so the whole model trains end to end. Each task can switch on a different number of skills. An orthogonality penalty keeps the skill embeddings distinct from one another. The method was tested on MacBERT with six Chinese NLU benchmarks and reached the best average F1. Its biggest gains were on token-level tasks. On three sentence-level datasets, however, single-task fine-tuning still scored higher. The main practical benefit is that task-skill mappings are learned rather than designed manually.
Key points
- Setup: MacBERT backbone with 7 skill FFNs per layer; MMoE and Skill-Net baselines also use 7 routines.
- Datasets: TNEWS, ChnSentiCorp, AFQMC, OCNLI, OntoNotesEE (NER) and CMRC2018 (span-extraction reading comprehension).
- Average F1: 66.40, compared with Skill-Net 65.82, single-task fine-tuning 66.01, MT-DNN 63.89 and MMoE 63.34.
- Largest gain: on OntoNotesEE the model scores 60.32 F1 against 44.92 for MMoE. It also leads on OCNLI and CMRC2018.
- Ablation: setting the orthogonality weight β to 0 lowers the average to 65.51 (−0.89). The architecture, not the penalty, accounts for most of the improvement.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 worksArts and Humanities · 17,450 worksLanguage and Linguistics · 17,296 works
Cite
Cite as Zhe Yang, Yi Huang, Yaqin Chen, Mengfei Guo, Xiaoting Wu and Junlan Feng. 2026. A Learnable Skill Combination Strategy for Multi-task Learning in Natural Language Understanding. Findings of the Association for Computational Linguistics: ACL 2026.
@inproceedings{yang2026learnable,
title = {{A Learnable Skill Combination Strategy for Multi-task Learning in Natural Language Understanding}},
author = {Zhe Yang, Yi Huang, Yaqin Chen, Mengfei Guo, Xiaoting Wu and Junlan Feng},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.1886},
url = {https://doi.org/10.18653/v1/2026.findings-acl.1886}
}References
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