DiffNeCTIS: Diffusion-based Nested Compound Type Identification for Sanskrit

Pretam Ray, Sinchani Chakraborty, Sriram Krishnan, Manoj Balaji Jagadeeshan, Pawan Goyal


Abstract
Sanskrit multi-component compounding presents a severe structured prediction challenge: the space of valid parse structures grows exponentially with compound length, implicit semantic relations are highly context-sensitive, and accurate type assignment demands simultaneous global structural coherence and local morphological precision across a fine-grained label typology. Existing systems address Nested Compound Type Identification for Sanskrit (NeCTIS) discriminatively, predicting dependency edges and semantic types in a single greedy pass. Reformulating NeCTIS as iterative generative refinement via diffusion over the full label sequence resolves this structural inconsistency but exposes a complementary bottleneck - coarse global attention that suppresses the localized morphological signals necessary for fine-grained type discrimination. We address this through a local refinement mechanism within a restricted window.

We further provide the first systematic evaluation of large language models on NeCTIS, finding consistent and substantial failures under zero-shot and few-shot conditions - attributable to the absence of structural inductive biases, Sanskrit under-representation in pretraining, and morphological sensitivity requirements that broad-coverage models are fundamentally ill-equipped to satisfy.
Anthology ID:
2026.emnlp-main.2378
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:
54021–54039
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2378/
DOI:
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Cite (ACL):
Pretam Ray, Sinchani Chakraborty, Sriram Krishnan, Manoj Balaji Jagadeeshan, and Pawan Goyal. 2026. DiffNeCTIS: Diffusion-based Nested Compound Type Identification for Sanskrit. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 54021–54039, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DiffNeCTIS: Diffusion-based Nested Compound Type Identification for Sanskrit (Ray et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2378.pdf