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We study the conditions under which the isometry of spaces with metrics generated by weights given on the edges of finite trees is equivalent to the isomorphism of these trees. Similar questions are studied for ultrametric spaces generated…

Metric Geometry · Mathematics 2020-02-18 Oleksiy Dovgoshey

We study the statistics of height and balanced height in the binary search tree problem in computer science. The search tree problem is first mapped to a fragmentation problem which is then further mapped to a modified directed polymer…

Statistical Mechanics · Physics 2009-11-07 Satya N. Majumdar , P. L. Krapivsky

Ultrametric matrices are a class of covariance matrices that arise in latent tree models. As a parameter space in a statistical model, the set of ultrametric matrices is neither convex nor a smooth manifold. Focus in the literature has…

Methodology · Statistics 2025-04-28 Tsung-Hung Yao , Zhenke Wu , Karthik Bharath , Veerabhadran Baladandayuthapani

Nonlinear metrics, such as the F1-score, Matthews correlation coefficient, and Fowlkes-Mallows index, are often used to evaluate the performance of machine learning models, in particular, when facing imbalanced datasets that contain more…

Machine Learning · Computer Science 2022-06-30 Emir Demirović , Peter J. Stuckey

Maxmin trees are labeled trees with the property that each vertex is either a local maximum or a local minimum. Such trees were originally introduced by Postnikov, who gave a formula to count them and different combinatorial interpretations…

Combinatorics · Mathematics 2019-02-06 William Dugan , Sam Glennon , Paul E. Gunnells , Einar Steingrimsson

We provide a new representation of an $\mathbb R$-tree by using a special set of metric rays. We have captured the four-point condition from these metric rays and shown an equivalence between the $\mathbb R$-trees with radial and river…

Metric Geometry · Mathematics 2018-03-29 Asuman G. Aksoy , Monariah Al-Ansari , Qidi Peng

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…

Combinatorics · Mathematics 2020-02-10 Momoko Hayamizu , Katharina T. Huber , Vincent Moulton , Yukihiro Murakami

Much information about a graph can be obtained by studying its spanning trees. On the other hand, a graph can be regarded as a 1-dimensional cell complex, raising the question of developing a theory of trees in higher dimension. As observed…

Combinatorics · Mathematics 2015-06-24 Art M. Duval , Caroline J. Klivans , Jeremy L. Martin

The early development of a zygote can be mathematically described by a developmental tree. To compare developmental trees of different species, we need to define distances on trees. If children cells after a division are not…

Combinatorics · Mathematics 2022-06-08 Yue Wang

We study infinite tree and ultrametric matrices, and their action on the boundary of the tree. For each tree matrix we show the existence of a symmetric random walk associated to it and we study its Green potential. We provide a…

Probability · Mathematics 2007-05-23 Claude Dellacherie , Servet Martinez , Jaime San Martin

There is a rising interest in mapping trees using satellite or aerial imagery, but there is no standardized evaluation protocol for comparing and enhancing methods. In dense canopy areas, the high variability of tree sizes and their spatial…

Computer Vision and Pattern Recognition · Computer Science 2023-11-15 Dimitri Gominski , Ankit Kariryaa , Martin Brandt , Christian Igel , Sizhuo Li , Maurice Mugabowindekwe , Rasmus Fensholt

A recurring theme in the least squares approach to phylogenetics has been the discovery of elegant combinatorial formulas for the least squares estimates of edge lengths. These formulas have proved useful for the development of efficient…

Combinatorics · Mathematics 2009-11-13 Radu Mihaescu , Lior Pachter

A half-tree is an edge configuration whose superimposition with a perfect matching is a tree. In this paper, we prove a half-tree theorem for the Pfaffian principal minors of a skew-symmetric matrix whose column sum is zero; introducing an…

Combinatorics · Mathematics 2014-01-21 Béatrice de Tilière

The objective of clustering is to discover natural groups in datasets and to identify geometrical structures which might reside there, without assuming any prior knowledge on the characteristics of the data. The problem can be seen as…

Computational Geometry · Computer Science 2018-01-26 Luis-Evaristo Caraballo , José-Miguel Díaz-Báñez , Nadine Kroher

Phylogenetic networks are a type of directed acyclic graph that represent how a set $X$ of present-day species are descended from a common ancestor by processes of speciation and reticulate evolution. In the absence of reticulate evolution,…

Combinatorics · Mathematics 2017-08-11 Andrew Francis , Charles Semple , Mike Steel

Projective metrics on vector spaces over finite fields, introduced by Gabidulin and Simonis in 1997, generalize classical metrics in coding theory like the Hamming metric, rank metric, and combinatorial metrics. While these specific metrics…

Metric Geometry · Mathematics 2025-05-13 Gabor Riccardi , Hugo Sauerbier Couvée

In this paper we prove a combinatorial theorem for finite labellings of trees, and show that it is equivalent to a theorem for finite covers of metric trees and a fixed point theorem on metric trees. We trace how these connections mimic the…

Combinatorics · Mathematics 2013-07-10 Andrew Niedermaier , Douglas Rizzolo , Francis Edward Su

There are several interrelated notions of discrete curvature on graphs. Many approaches utilize the optimal transportation metric on its probability simplex or the distance matrix of the graph. In this survey article, we compute formulas…

Combinatorics · Mathematics 2025-11-04 Sawyer Jack Robertson

We investigate a canonical extension of a conventional combinatorial notion of reduced divisors to a notion of tropical projections, which can be defined as the unique minimizers of the so-called $B$-pseudonorms with respect to compact…

Combinatorics · Mathematics 2018-12-04 Ye Luo

A matching complex of a simple graph $G$ is a simplicial complex with faces given by the matchings of $G$. The topology of matching complexes is mysterious; there are few graphs for which the homotopy type is known. Marietti and Testa…

Combinatorics · Mathematics 2021-02-01 Marija Jelić Milutinović , Helen Jenne , Alex McDonough , Julianne Vega