arXiv Machine Learning

Is the Geometry Doing the Work? An Operating-Point Audit of Hierarchy in Hyperbolic Vision-Language Models

arXiv:2607. 05268v1 Announce Type: cross Abstract: Whether a hyperbolic representation model uses its geometry cannot be read off its curvature parameter: what matters is the dimensionless operating point $\sqrt{c}\rho$ and whether the radial and cone machinery is active there.

arXiv Computer Vision
Aug 25

Hyper^2: Unleashing Hyperbolic Geometry's Full Potential via Dual-Space Consistency

The paper introduces Hyper^2, a dual‑space consistency framework that applies hyperbolic geometry consistently to both the loss and the encoder in point‑cloud completion tasks. By reusing the same arcosh(1+αd²) function as a positional bias in refinement attention and as the Chamfer loss, Hyper^2 achieves significant Chamfer error reductions—up to 22.9% on ShapeNet‑55 and 37.5% on unseen ShapeNet‑34—while adding only ~1.6% FLOPs. The authors demonstrate that geometric consistency across encoder and loss, rather than either component alone, is key to effective hyperbolic supervision, supported by two model‑agnostic indicators that peak only when both are hyperbolic.

By Guantian Zheng, Haiyang Xu, Tianyu Gao
arXiv Computer Vision
Sep 23

What Drives Hierarchy-Aware Image Retrieval? Taxonomy Alignment, Objective Choice, and Geometry

The paper investigates why hierarchical image retrieval improves when using frozen DINOv2 features. It compares Euclidean and hyperbolic embeddings trained with taxonomy-distance regression or a taxonomy-aware supervised contrastive objective, finding that the choice of loss function (objective family) contributes more to hierarchy-aware performance than the geometry of the embedding space. Semantic alignment of the taxonomy also plays a significant role, while stronger negative curvature does not explain the gains.

By Ling Shi (Southeast University)
arXiv AI
Sep 24

A Hierarchy-Aware Video-Language Model Evaluation and Hyperbolic Baseline for Surgery

The paper introduces SurgHiBench, a hierarchy-aware evaluation suite for surgical video understanding that measures recognition, consistency, and severity across different granularity levels. It also presents HyperSurg, a hyperbolic model that enforces phase-step containment using entailment cones, evaluated on four datasets covering three procedure types. The study shows that models with identical accuracy can differ significantly in error severity, and that hyperbolic geometry improves predictions by aligning them with the procedural hierarchy.

By Ana Manzano Rodr\'iguez, Pascal Mettes, Marlies P. Schijven, Cees G. M. Snoek
arXiv Computer Vision
Sep 25

Seeing Is Not Measuring: Tool-Augmented Metric Spatial Reasoning for Vision-Language Models

The paper introduces a tool‑augmented framework that enhances a small Vision‑Language Model (Qwen3.5‑4B) with geometric tools—3D object detection, metric depth estimation, and deterministic solvers for distance, size, and bearing—to improve metric spatial reasoning. By moving metric computation from the model’s weights into explicit solvers, the approach achieves significant gains on ReVSI‑Bench tasks, notably increasing absolute distance accuracy from 0.46 to 0.74 MRA and relative direction accuracy from 25.9% to 73.4%. The modular design allows swapping in different detectors, enabling a clear separation between perception and reasoning errors, and the model can autonomously sequence the tools to match a scripted pipeline on most tasks.

By Kai Glantz, Clemens Grange
arXiv Machine Learning
Sep 18

Stiefel Attention: When the Geometry of Transformer Projection Matrices Dominates Optimizer Choice---and When It Does Not

The paper introduces Stiefel Attention, which constrains the query and key projection matrices of transformers to the Stiefel manifold and optimizes them with a Riemannian Adam variant. It demonstrates that this approach yields steepest‑descent updates, is well‑conditioned, and preserves learned attention geometry during weight decay. Empirical results show significant accuracy gains on modular arithmetic grokking and CIFAR‑10 patches, with the improvement attributed to a step‑scale‑free update rule rather than equivariance or projector changes.

By Rub\'en Dar\'io Guerrero