Recognizing and realizing cactus metrics

Momoko Hayamizu, Katharina Huber, Vincent Moulton, Yukihiro Murakami

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
19 Downloads (Pure)


The problem of realizing finite metric spaces in terms of weighted graphs has many applications. For example, the mathematical and computational properties of metrics that can be realized by trees have been well-studied and such research has laid the foundation of the reconstruction of phylogenetic trees from evolutionary distances. However, as trees may be too restrictive to accurately represent real-world data or phenomena, it is important to understand the relationship between more general graphs and distances. In this paper, we introduce a new type of metric called a cactus metric, that is, a metric that can be realized by a cactus graph. We show that, just as with tree metrics, a cactus metric has a unique optimal realization. In addition, we describe an algorithm that can recognize whether or not a metric is a cactus metric and, if so, compute its optimal realization in $O(n^3)$ time, where $n$ is the number of points in the space.
Original languageEnglish
Article number105916
Number of pages5
JournalInformation Processing Letters
Early online date16 Jan 2020
Publication statusPublished - 1 May 2020


  • Algorithms
  • Cactus metric
  • Metric realization
  • Optimal realization
  • Phylogenetic network

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