Some Assembly Required: Pointer-Decoded Seq2Seq Models for German Without a Native Seq2Seq Backbone

Jan Pfister, Tom Völker, Andreas Hotho


Abstract
Pointer-decoded Seq2Seq transformers remain a strong recipe for aspect-based sentiment analysis (ABSA), but native German Seq2Seq backbones remain scarce, and current pretraining trends favor decoder-only architectures. Existing assembly recipes disagree on which pairings work. We therefore study models assembled from independently pretrained encoder and decoder LMs, primarily on German ABSA, where fixed pointer outputs expose both tuple accuracy and grammar violations. All nine backbone combinations train under both separate and parameter-sharing merged cross-attention, with separate attention slightly stronger overall. Depth and scale sweeps show that additional capacity pays off more on the encoder side for these pointer-decoded tasks, and our strongest two-stack assembly trails mBART but outperforms mT5-small on both German datasets. Motivated by decoder-only pretraining, we replace the encoder and decoder with one backbone that encodes the source and autoregressively produces pointer queries. Bidirectional source visibility and scale matter more consistently than pointer-query refinement: a 120M LLäMmlein model exceeds both same-family two-stack means with roughly half the parameters, and a 1B ModernGBERT reaches mBART-level performance.
Anthology ID:
2026.findings-emnlp.2464
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
53012–53027
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2464/
DOI:
Bibkey:
Cite (ACL):
Jan Pfister, Tom Völker, and Andreas Hotho. 2026. Some Assembly Required: Pointer-Decoded Seq2Seq Models for German Without a Native Seq2Seq Backbone. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 53012–53027, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Some Assembly Required: Pointer-Decoded Seq2Seq Models for German Without a Native Seq2Seq Backbone (Pfister et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2464.pdf