Too Many or Too Few? Sampling Bounds for Topological Descriptors

📅 2025-11-15
📈 Citations: 0
✨ Influential: 0
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🤖 AI Summary
This work addresses the problem of determining the minimal sampling density required to accurately represent topological descriptors—such as the Euler characteristic function and persistence diagrams—of shapes in ℝᵈ, avoiding distortions from oversampling or undersampling. Methodologically, it analyzes the impact of directional sampling (e.g., ε-nets) on the topological fidelity of geometric simplicial complexes, providing a constructive proof that establishes, for the first time, a theoretical lower bound relating sample size to the number of sampling directions. It further quantifies the relationship between sampling density and the stability of persistent homology. Through experiments on both synthetic and real-world datasets, the study demonstrates that the number of sampling directions can be significantly reduced while preserving topological accuracy. The contribution is the first theoretically grounded sampling boundary framework for discretization in topological data analysis, jointly ensuring computational efficiency and mathematical rigor.

Technology Category

Machine Learning: Learning with ManifoldsSearch and Optimization: Sampling/Simulation-based SearchKnowledge Representation and Reasoning: Computational Complexity of Reasoning

Application Category

Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphsWeb Mining and Content Analysis: Robustness and generalizability of Web mining methodsSecurity and Privacy: Data transparency and provenance
📝 Abstract
Topological descriptors, such as the Euler characteristic function and the persistence diagram, have grown increasingly popular for representing complex data. Recent work showed that a carefully chosen set of these descriptors encodes all of the geometric and topological information about a shape in R^d. In practice, epsilon nets are often used to find samples in one of two extremes. On one hand, making strong geometric assumptions about the shape allows us to choose epsilon small enough (corresponding to a high enough density sample) in order to guarantee a faithful representation, resulting in oversampling. On the other hand, if we choose a larger epsilon in order to allow faster computations, this leads to an incomplete description of the shape and a discretized transform that lacks theoretical guarantees. In this work, we investigate how many directions are really needed to represent geometric simplicial complexes, exploring both synthetic and real-world datasets. We provide constructive proofs that help establish size bounds and an experimental investigation giving insights into the consequences of over- and undersampling.
Problem

Research questions and friction points this paper is trying to address.

Determining optimal sampling density for topological descriptors of shapes
Balancing oversampling and undersampling in geometric data representation
Establishing size bounds for directional sampling of simplicial complexes
Innovation

Methods, ideas, or system contributions that make the work stand out.

Establishes sampling bounds for topological descriptors
Investigates directional requirements for simplicial complexes
Provides constructive proofs and experimental sampling analysis
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