VLM embeddings show an emergent radial entailment hierarchy, improvable by fine-tuning

Alper & Averbuch-Elor propose Radial Embedding, treating the empty-string embedding as an entailment root and concept genericity as Euclidean distance from it, an explicit relaxation of hyperbolic entailment cones [alper-averbuch-elor-2024-radial-embedding] Zero-shot, CLIP-Base reaches order-consistency tau_d=0.89 and OpenCLIP-H tau_d=0.83 on their HierarCaps benchmark, surpassing prior purpose-built models [alper-averbuch-elor-2024-radial-embedding] Fine-tuning only the text encoder with a contrastive exterior-angle loss raises tau_d to 0.99 (CLIP-Base) and 0.97 (OpenCLIP-H) and HyperLex correlation from 0.06 to 0.37 [alper-averbuch-elor-2024-radial-embedding] The fine-tuning leaves standard multimodal tasks (COCO retrieval, CIFAR classification) near-unchanged, ruling out a general-capability side effect [alper-averbuch-elor-2024-radial-embedding]