M-VLM2Vec: Structure-Preserving Matryoshka Representation Learning for Vision-Language Embeddings

Minh Khoi Nguyen Do, Nguyen Hong Dang, Danh Vinh Le, Minh Quoc Nhat Nguyen, Linh Ngo Van, Duc Anh Nguyen, Trung Le


Abstract
Deploying high-dimensional Vision-Language Model (VLM) embeddings is computationally prohibitive. While Matryoshka Representation Learning (MRL) allows elastic truncation, standard MRL optimizes dimensional hierarchies semi-independently. This lack of cross-scale structural constraints creates a severe topological disconnect causing representational collapse at lower dimensions and introduces optimization trade-offs that compromise high-dimensional capacity. To solve this, we propose **M-VLM2Vec**, a framework that shifts MRL from a compromised hierarchy to a synergistic geometric structure. Without additional supervision, we integrate two novel constraints into the multimodal contrastive objective: (1) Laplacian spectral alignment to preserve the global manifold topology across scales, and (2) Stiefel-constrained orthogonal projection to bidirectionally align local contrastive landscapes. By allowing nested spaces to mutually regularize, M-VLM2Vec eliminates competing gradients, preventing ultra-low-dimensional collapse while yielding striking, consistent performance gains across all embedding scales on the Multimodal Embedding Benchmark (MMEB).
Anthology ID:
2026.findings-emnlp.308
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:
6515–6537
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URL:
https://aclanthology.org/2026.findings-emnlp.308/
DOI:
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Cite (ACL):
Minh Khoi Nguyen Do, Nguyen Hong Dang, Danh Vinh Le, Minh Quoc Nhat Nguyen, Linh Ngo Van, Duc Anh Nguyen, and Trung Le. 2026. M-VLM2Vec: Structure-Preserving Matryoshka Representation Learning for Vision-Language Embeddings. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 6515–6537, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
M-VLM2Vec: Structure-Preserving Matryoshka Representation Learning for Vision-Language Embeddings (Do et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.308.pdf