English

PHyCLIP: $\ell_1$-Product of Hyperbolic Factors Unifies Hierarchy and Compositionality in Vision-Language Representation Learning

Computer Vision and Pattern Recognition 2026-03-03 v2 Machine Learning

Abstract

Vision-language models have achieved remarkable success in multi-modal representation learning from large-scale pairs of visual scenes and linguistic descriptions. However, they still struggle to simultaneously express two distinct types of semantic structures: the hierarchy within a concept family (e.g., dog \preceq mammal \preceq animal) and the compositionality across different concept families (e.g., "a dog in a car" \preceq dog, car). Recent works have addressed this challenge by employing hyperbolic space, which efficiently captures tree-like hierarchy, yet its suitability for representing compositionality remains unclear. To resolve this dilemma, we propose PHyCLIP, which employs an 1\ell_1-Product metric on a Cartesian product of Hyperbolic factors. With our design, intra-family hierarchies emerge within individual hyperbolic factors, and cross-family composition is captured by the 1\ell_1-product metric, analogous to a Boolean algebra. Experiments on zero-shot classification, retrieval, hierarchical classification, and compositional understanding tasks demonstrate that PHyCLIP outperforms existing single-space approaches and offers more interpretable structures in the embedding space.

Keywords

Cite

@article{arxiv.2510.08919,
  title  = {PHyCLIP: $\ell_1$-Product of Hyperbolic Factors Unifies Hierarchy and Compositionality in Vision-Language Representation Learning},
  author = {Daiki Yoshikawa and Takashi Matsubara},
  journal= {arXiv preprint arXiv:2510.08919},
  year   = {2026}
}

Comments

24 pages. Codes are available at https://github.com/tksmatsubara/PHyCLIP