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Over some types of trees with a given number of vertices, which trees minimize or maximize the total number of subtrees or leaf containing subtrees are studied. Here are some of the main results:\ (1)\, Sharp upper bound on the total number…

Combinatorics · Mathematics 2012-06-15 Shuchao Li , Shujing Wang

Phylogenetic (evolutionary) trees and networks are leaf-labeled graphs that are widely used to represent the evolutionary relationships between entities such as species, languages, cancer cells, and viruses. To reconstruct and analyze…

Data Structures and Algorithms · Computer Science 2023-08-21 Michael J. Dinneen , Pankaj S. Ghodla , Simone Linz

In this paper, we give a constructive proof of the fact that the treewidth of a graph is at most its divisorial gonality. The proof gives a polynomial time algorithm to construct a tree decomposition of width at most $k$, when an effective…

Discrete Mathematics · Computer Science 2020-05-13 Hans L. Bodlaender , Josse van Dobben de Bruyn , Dion Gijswijt , Harry Smit

Rotation distance between rooted binary trees measures the number of simple operations it takes to transform one tree into another. There are no known polynomial-time algorithms for computing rotation distance. We give an efficient,…

Data Structures and Algorithms · Computer Science 2018-03-19 Sean Cleary , Katherine St. John

We contribute towards resolving the open question of how many hidden layers are required in ReLU networks for exactly representing all continuous and piecewise linear functions on $\mathbb{R}^d$. While the question has been resolved in…

Machine Learning · Computer Science 2025-10-24 Moritz Grillo , Christoph Hertrich , Georg Loho

A chief problem in phylogenetics and database theory is the computation of a maximum consistent tree from a set of rooted or unrooted trees. A standard input are triplets, rooted binary trees on three leaves, or quartets, unrooted binary…

Discrete Mathematics · Computer Science 2010-05-31 Leo van Iersel , Matthias Mnich

We describe a kernel of size 9k-8 for the NP-hard problem of computing the Tree Bisection and Reconnect (TBR) distance k between two unrooted binary phylogenetic trees. We achieve this by extending the existing portfolio of reduction rules…

Data Structures and Algorithms · Computer Science 2022-09-21 Steven Kelk , Simone Linz , Ruben Meuwese

We study the growth behaviour of rational linear recurrence sequences. We show that for low-order sequences, divergence is decidable in polynomial time. We also exhibit a polynomial-time algorithm which takes as input a divergent rational…

Computational Complexity · Computer Science 2021-11-22 Shaull Almagor , Brynmor Chapman , Mehran Hosseini , Joël Ouaknine , James Worrell

The robust and efficient recognition of visual relations in images is a hallmark of biological vision. We argue that, despite recent progress in visual recognition, modern machine vision algorithms are severely limited in their ability to…

Computer Vision and Pattern Recognition · Computer Science 2018-05-28 Matthew Ricci , Junkyung Kim , Thomas Serre

It is proved that the rectilinear crossing number of every graph with bounded tree-width and bounded degree is linear in the number of vertices. **** This paper has been withdrawn by the author. **** The results have been superseeded by the…

Combinatorics · Mathematics 2007-05-23 David R. Wood

Hybrid evolution and horizontal gene transfer (HGT) are processes where evolutionary relationships may more accurately be described by a reticulated network than by a tree. In such a network, there will often be several paths between any…

Populations and Evolution · Quantitative Biology 2014-09-24 Andrew R. Francis , Mike Steel

The {\sc Directed Maximum Leaf Out-Branching} problem is to find an out-branching (i.e. a rooted oriented spanning tree) in a given digraph with the maximum number of leaves. In this paper, we improve known parameterized algorithms and…

Data Structures and Algorithms · Computer Science 2007-07-10 Noga Alon , Fedor V. Fomin , Gregory Gutin , Michael Krivelevich , Saket Saurabh

We study the expressivity of rational neural networks (RationalNets) through the lens of algebraic geometry. We consider rational functions that arise from a given RationalNet to be tuples of fractions of homogeneous polynomials of fixed…

Algebraic Geometry · Mathematics 2025-09-16 Alexandros Grosdos , Elina Robeva , Maksym Zubkov

Let X be a complex, Gorenstein, Q-factorial, toric Fano variety. We prove two conjectures on the maximal Picard number of X in terms of its dimension and its pseudo-index, and characterize the boundary cases. Equivalently, we determine the…

Algebraic Geometry · Mathematics 2007-05-23 C. Casagrande

The structure of an evolving network contains information about its past. Extracting this information efficiently, however, is, in general, a difficult challenge. We formulate a fast and efficient method to estimate the most likely history…

Physics and Society · Physics 2020-09-16 Gábor Timár , Rui A. da Costa , Sergey N. Dorogovtsev , José F. F. Mendes

We consider the problem of embedding the Steiner points of a Steiner tree with given topology into the rectilinear plane. Thereby, the length of the path between a distinguished terminal and each other terminal must not exceed given length…

Data Structures and Algorithms · Computer Science 2015-08-19 Jens Maßberg

Neural networks with piecewise linear activation functions, such as rectified linear units (ReLU) or maxout, are among the most fundamental models in modern machine learning. We make a step towards proving lower bounds on the size of such…

Combinatorics · Mathematics 2026-05-29 Christoph Hertrich , Georg Loho

Phylogenetic networks have gained prominence over the years due to their ability to represent complex non-treelike evolutionary events such as recombination or hybridization. Popular combinatorial objects used to construct them are triplet…

Combinatorics · Mathematics 2016-10-19 P. Gambette , K. T. Huber , S. Kelk

Tree-child networks are an important class of phylogenetic network used to model reticulate evolutionary processes. These networks have attracted increasing attention from researchers with interests in both combinatorics and algorithms. A…

Combinatorics · Mathematics 2026-05-11 Hexuan Liu , Michael Wallner , Guan-Ru Yu

We study the problem of visualizing phylogenetic networks, which are extensions of the Tree of Life in biology. We use a space filling visualization method, called DAGmaps, in order to obtain clear visualizations using limited space. In…

Data Structures and Algorithms · Computer Science 2016-09-06 Ioannis G. Tollis , Konstantinos G. Kakoulis