Clustering in hyperbolic balls
This work addresses the need for efficient data analysis techniques in hyperbolic machine learning, which is important for researchers in this emerging field.
The paper establishes a rigorous mathematical framework for clustering in hyperbolic spaces by introducing k-means clustering based on a novel barycenter definition and an EM algorithm for learning mixtures of probability distributions in hyperbolic balls, laying the foundation for unsupervised learning in this domain.
The idea of representations of the data in negatively curved manifolds recently attracted a lot of attention and gave a rise to the new research direction named {\it hyperbolic machine learning} (ML). In order to unveil the full potential of this new paradigm, efficient techniques for data analysis and statistical modeling in hyperbolic spaces are necessary. In the present paper rigorous mathematical framework for clustering in hyperbolic spaces is established. First, we introduce the $k$-means clustering in hyperbolic balls, based on the novel definition of barycenter. Second, we present the expectation-maximization (EM) algorithm for learning mixtures of novel probability distributions in hyperbolic balls. In such a way we lay the foundation of unsupervised learning in hyperbolic spaces.