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This paper presents new graph-theoretic conditions for structural target controllability of directed networks. After reviewing existing conditions and highlighting some gaps in the literature, we introduce a new class of network systems,…

Systems and Control · Electrical Eng. & Systems 2025-04-25 Marco Peruzzo , Giacomo Baggio , Francesco Ticozzi

The connected tree-width of a graph is the minimum width of a tree-decomposition whose parts induce connected subgraphs. Long cycles are examples of graphs that have small tree-width but large connected tree-width. We show that a graph has…

Combinatorics · Mathematics 2015-10-15 Reinhard Diestel , Malte Müller

A criterion for subnormality of unbounded composition operators in L2-spaces, written in terms of measurable families of probability measures satisfying the so-called consistency condition, is established. It becomes a new characterization…

Functional Analysis · Mathematics 2013-03-27 Piotr Budzynski , Zenon Jan Jablonski , Il Bong Jung , Jan Stochel

Many applications in network science have recently been discovered for the "curvature" of a network, but there is no consensus on the definition for this term. A common approach in these applications is to derive from the curvature either a…

Combinatorics · Mathematics 2021-12-24 Matthew Yancey

The connections in many networks are not merely binary entities, either present or not, but have associated weights that record their strengths relative to one another. Recent studies of networks have, by and large, steered clear of such…

Statistical Mechanics · Physics 2009-11-10 M. E. J. Newman

Let $G$ be a group. The directed endomorphism graph, \dend of $G$ is a directed graph with vertex set $G$ and there is a directed edge from the vertex `$a$' to the vertex `$\, b$' $(a \neq b) $ if and only if there exists an endomorphism on…

Combinatorics · Mathematics 2025-12-16 Midhuna V Ajith , Mainak Ghosh , Aparna Lakshmanan S

In this series, we introduce and investigate the concept of connectoids, which captures the connectivity structure of various discrete objects such as undirected graphs, directed graphs, bidirected graphs, hypergraphs and finitary matroids.…

Combinatorics · Mathematics 2026-05-21 Nathan Bowler , Florian Reich

Random graphs are more and more used for modeling real world networks such as evolutionary networks of proteins. For this purpose we look at two different models and analyze how properties like connectedness and degree distributions are…

Probability · Mathematics 2019-02-05 Klemens Taglieber , Uta Freiberg

In resonance to a recent geometric framework proposed by Douglas and Yang, a functional model for certain linear bounded operators with rank-one self-commutator acting on a Hilbert space is developed. By taking advantage of the refined…

Functional Analysis · Mathematics 2018-10-31 Björn Gustafsson , Mihai Putinar

An oriented graph is a directed graph without any cycle of length at most 2. To push a vertex of a directed graph is to reverse the orientation of the arcs incident to that vertex. Klostermeyer and MacGillivray defined push graphs which are…

Discrete Mathematics · Computer Science 2015-08-31 Sagnik Sen

A graphical model provides a compact and efficient representation of the association structure of a multivariate distribution by means of a graph. Relevant features of the distribution are represented by vertices, edges and other…

Statistics Theory · Mathematics 2020-09-03 Alberto Roverato , Robert Castelo

We study the matrices Q_k of in-forests of a weighted digraph G and their connections with the Laplacian matrix L of G. The (i,j) entry of Q_k is the total weight of spanning converging forests (in-forests) with k arcs such that i belongs…

Combinatorics · Mathematics 2007-05-23 Pavel Chebotarev , Rafig Agaev

Let $(G,w)$ be a weighted graph with a weight-function $w: E(G)\to \mathbb R\backslash\{0\}$. A weighted graph $(G,w)$ is invertible to a new weighted graph if its adjacency matrix is invertible. A graph inverse has combinatorial interest…

Combinatorics · Mathematics 2015-06-15 Dong Ye , Yujun Yang , Bholanath Mandal , Douglas J. Klein

We propose to use a simulation driven inverse inference approach to model the dynamics of tree branches under manipulation. Learning branch dynamics and gaining the ability to manipulate deformable vegetation can help with occlusion-prone…

Robotics · Computer Science 2023-12-21 Jayadeep Jacob , Tirthankar Bandyopadhyay , Jason Williams , Paulo Borges , Fabio Ramos

It is well-known that, in Linear Dynamics, the most studied class of linear operators is certainly that of weighted shifts, on the separable Banach spaces $c_0$ and $\ell^p$, $1 \leq p< \infty$. Over the last decades, the intensive study of…

Dynamical Systems · Mathematics 2022-10-05 Emma D'Aniello , Martina Maiuriello

Given any two forests (pseudoforests) with the same degree sequence, we show that one can be transformed into the other by a sequence of 2-switches in such a way that all the intermediate graphs of the transformation are forests…

Combinatorics · Mathematics 2026-03-12 Victor N. Schvöllner , Adrián Pastine , Daniel A. Jaume

Two-side estimates for two-weighted discrete Hardy-type operators on a tree are obtained. For general weights we prove the discrete analogue of Evans - Harris - Pick theorem (it is a quite simple consequence from their result). It gives the…

Functional Analysis · Mathematics 2013-11-05 A. A. Vasil'eva

We introduce a class of linear bounded invertible operators on Banach spaces, called shift operators, which comprises weighted backward shifts and models finite products of weighted backward shifts and dissipative composition operators. We…

Dynamical Systems · Mathematics 2024-07-31 Maria Carvalho , Udayan B. Darji , Paulo Varandas

We propose a tree-based algorithm for classification and regression problems in the context of functional data analysis, which allows to leverage representation learning and multiple splitting rules at the node level, reducing…

Machine Learning · Statistics 2020-11-03 Edoardo Belli , Simone Vantini

This paper begins the study of reconfiguration of zero forcing sets, and more specifically, the zero forcing graph. Given a base graph $G$, its zero forcing graph, $\mathscr{Z}(G)$, is the graph whose vertices are the minimum zero forcing…

Combinatorics · Mathematics 2020-09-02 Jesse Geneson , Ruth Haas , Leslie Hogben