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Local Manifold Explanations with Tangent Space Regression
Proceedings of the 2nd Conference on Topology, Algebra, and Geometry in Data Science(TAG-DS 2026), PMLR 334(2):279-297, 2026.
Abstract
Low-dimensional manifold learning is used to embed and visualize high-dimensional data, revealing its underlying geometry. However, identifying which features drive local variation along the manifold remains difficult. Many post-hoc explanation methods target explaining extrinsic embedding coordinates rather than intrinsic manifold structure, or provide only global explanations. In this work, we introduce Local Tangent Space Regression Explanations (LTSREx)), a method to explain the local structure of a manifold in terms of interpretable features by performing sparse linear regression in the tangent space of the manifold at each point, coupled with Tikhonov denoising via the connection Laplacian to ensure that explanations are consistent and vary smoothly across nearby points. We show that our method produces meaningful local explanations on synthetic data, rotated MNIST digits, and two single-cell gene expression datasets. Our code is available at https://github.com/he-jesse/LTSREx.