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We present new short proofs of known spanning tree enumeration formulae for threshold and Ferrers graphs by showing that the Laplacian matrices of such graphs admit triangular rank-one perturbations. We then characterize the set of graphs…

Combinatorics · Mathematics 2021-03-26 Christian Go , Zhong Xuan Khwa , Xinyu Luo , Matthew T. Stamps

Characterization of k-chordal graphs based on the existence of a "simplicial path" was shown in [Chv{\'a}tal et al. Note: Dirac-type characterizations of graphs without long chordless cycles. Discrete Mathematics, 256, 445-448, 2002]. We…

Combinatorics · Mathematics 2013-01-01 R. Krithika , Rogers Mathew , N. S. Narayanaswamy , N. Sadagopan

Using the method of spectral decimation and a modified version of Kirchhoffs Matrix-Tree Theorem, a closed form solution to the number of spanning trees on approximating graphs to a fully symmetric self-similar structure on a finitely…

Combinatorics · Mathematics 2012-12-03 Jason A. Anema

The purposes of this note are the following two; we first generalize Okada-Takeuti's well quasi ordinal diagram theory, utilizing the recent result of Dershowitz-Tzameret's version of tree embedding theorem with gap conditions. Second, we…

Logic in Computer Science · Computer Science 2019-02-07 Mitsuhiro Okada , Yuta Takahashi

A tree with at most k leaves is called k-ended tree, and a tree with exactly k leaves is called k-end tree, where a leaf is a vertex of degree one. Contraction of a graph G along the edge e means deleting the edge e and identifying its end…

Combinatorics · Mathematics 2016-12-30 Hamed Ghasemian Zoeram

The decycling number of a graph $G$ is the minimum number of vertices whose removal from $G$ results in an acyclic subgraph. It is known that determining the decycling number of a graph $G$ is equivalent to finding the maximum induced…

Combinatorics · Mathematics 2018-09-20 Jian Wang , Xirong Xu

We prove that finding a rooted subtree with at least $k$ leaves in a digraph is a fixed parameter tractable problem. A similar result holds for finding rooted spanning trees with many leaves in digraphs from a wide family $\cal L$ that…

Data Structures and Algorithms · Computer Science 2007-05-23 Noga Alon , Fedor Fomin , Gregory Gutin , Michael Krivelevich , Saket Saurabh

We call a topological ordering of a weighted directed acyclic graph non-negative if the sum of weights on the vertices in any prefix of the ordering is non-negative. We investigate two processes for constructing non-negative topological…

Combinatorics · Mathematics 2016-09-21 Dániel Gerbner , Balázs Keszegh , Cory Palmer , Dömötör Pálvölgyi

We study various representations for cyclic lambda-terms as higher-order or as first-order term graphs. We focus on the relation between 'lambda-higher-order term graphs' (lambda-ho-term-graphs), which are first-order term graphs endowed…

Logic in Computer Science · Computer Science 2013-02-27 Clemens Grabmayer , Jan Rochel

We prove that every graph which admits a tree-decomposition into finite parts has a rooted tree-decomposition into finite parts that is linked, tight and componental. As an application, we obtain that every graph without half-grid minor has…

Combinatorics · Mathematics 2024-05-14 Sandra Albrechtsen , Raphael W. Jacobs , Paul Knappe , Max Pitz

An algorithm for generating the structure of a directed acyclic graph from data using the notion of causal input lists is presented. The algorithm manipulates the ordering of the variables with operations which very much resemble arc…

Artificial Intelligence · Computer Science 2013-03-25 Remco R. Bouckaert

We propose a novel graph clustering method guided by additional information on the underlying structure of the clusters (or communities). The problem is formulated as the matching of a graph to a template with smaller dimension, hence…

Machine Learning · Statistics 2021-07-06 Mateus Riva , Florian Yger , Pietro Gori , Roberto M. Cesar , Isabelle Bloch

There are many classes of nonsimple graph C*-algebras that are classified by the six-term exact sequence in K-theory. In this paper we consider the range of this invariant and determine which cyclic six-term exact sequences can be obtained…

Operator Algebras · Mathematics 2015-10-30 Søren Eilers , Takeshi Katsura , Mark Tomforde , James West

For a finite simplicial graph $\Gamma$, let $A(\Gamma)$ denote the right-angled Artin group on $\Gamma$. Recently Kim and Koberda introduced the extension graph $\Gamma^e$ for $\Gamma$, and established the Extension Graph Theorem: for…

Geometric Topology · Mathematics 2018-07-03 Eon-Kyung Lee , Sang-Jin Lee

Directed graphs are widely used to model data flow and execution dependencies in streaming applications. This enables the utilization of graph partitioning algorithms for the problem of parallelizing computation for multiprocessor…

Data Structures and Algorithms · Computer Science 2017-09-26 Orlando Moreira , Merten Popp , Christian Schulz

We study the minimal spanning arborescence which is the directed analogue of the minimal spanning tree, with a particular focus on its infinite volume limit and its geometric properties. We prove that in a certain large class of transient…

Probability · Mathematics 2024-01-26 Gourab Ray , Arnab Sen

Directed acyclic graphs (DAGs) are a class of graphs commonly used in practice, with examples that include electronic circuits, Bayesian networks, and neural architectures. While many effective encoders exist for DAGs, it remains…

Machine Learning · Computer Science 2025-05-30 Michael Sun , Orion Foo , Gang Liu , Wojciech Matusik , Jie Chen

A relaxed $k$-ary tree is an ordered directed acyclic graph with a unique source and sink in which every node has out-degree $k$. These objects arise in the compression of trees in which some repeated subtrees are factored and repeated…

Combinatorics · Mathematics 2024-04-15 Manosij Ghosh Dastidar , Michael Wallner

We develop a structural approach to simultaneous embeddability in temporal sequences of graphs, inspired by graph minor theory. Our main result is a classification theorem for 2-connected temporal sequences: we identify five obstruction…

Combinatorics · Mathematics 2025-04-02 Johannes Carmesin , Will J. Turner

Random directed acyclic graphs (DAGs) based on imposing an order on Erd\H{o}s-R\'enyi and scale free random graphs are widely used for evaluating causal discovery algorithms. We show that in such DAGs, the set of nodes reachable via open…

Methodology · Statistics 2026-05-08 Alexander G. Reisach , Antoine Chambaz , Gilles Blanchard , Sebastian Weichwald