An objective function for order preserving hierarchical clustering

Fuente: arXiv
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Main Author: Bakkelund, Daniel
Format: Preprint
Published: 2021
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author Bakkelund, Daniel
author_facet Bakkelund, Daniel
contents We present a theory and an objective function for similarity-based hierarchical clustering of probabilistic partial orders and directed acyclic graphs (DAGs). Specifically, given elements $x \le y$ in the partial order, and their respective clusters $[x]$ and $[y]$, the theory yields an order relation $\le'$ on the clusters such that $[x]\le'[y]$. The theory provides a concise definition of order-preserving hierarchical clustering, and offers a classification theorem identifying the order-preserving trees (dendrograms). To determine the optimal order-preserving trees, we develop an objective function that frames the problem as a bi-objective optimisation, aiming to satisfy both the order relation and the similarity measure. We prove that the optimal trees under the objective are both order-preserving and exhibit high-quality hierarchical clustering. Since finding an optimal solution is NP-hard, we introduce a polynomial-time approximation algorithm and demonstrate that the method outperforms existing methods for order-preserving hierarchical clustering by a significant margin.
format Preprint
id arxiv_https___arxiv_org_abs_2109_04266
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle An objective function for order preserving hierarchical clustering
Bakkelund, Daniel
Machine Learning
Combinatorics
62H30, 06A06
G.1.2; G.1.6; G.2.2; I.2.6; I.5.3
We present a theory and an objective function for similarity-based hierarchical clustering of probabilistic partial orders and directed acyclic graphs (DAGs). Specifically, given elements $x \le y$ in the partial order, and their respective clusters $[x]$ and $[y]$, the theory yields an order relation $\le'$ on the clusters such that $[x]\le'[y]$. The theory provides a concise definition of order-preserving hierarchical clustering, and offers a classification theorem identifying the order-preserving trees (dendrograms). To determine the optimal order-preserving trees, we develop an objective function that frames the problem as a bi-objective optimisation, aiming to satisfy both the order relation and the similarity measure. We prove that the optimal trees under the objective are both order-preserving and exhibit high-quality hierarchical clustering. Since finding an optimal solution is NP-hard, we introduce a polynomial-time approximation algorithm and demonstrate that the method outperforms existing methods for order-preserving hierarchical clustering by a significant margin.
title An objective function for order preserving hierarchical clustering
topic Machine Learning
Combinatorics
62H30, 06A06
G.1.2; G.1.6; G.2.2; I.2.6; I.5.3
url https://arxiv.org/abs/2109.04266