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The entities in directed networks arising from real-world interactions are often naturally organized under some hierarchical structure. Given a directed, weighted, graph with edges and node labels, we introduce ranking problem where the…

Data Structures and Algorithms · Computer Science 2025-02-04 Chamalee Wickrama Arachchi , Nikolaj Tatti

By natural way the hierarchy structure is introduced on directed graphs with weighted adjacencies. Embedded system of algebras of subsets of the set of vertices of such digraph and it's consolidations, which vertices are the elementary sets…

Combinatorics · Mathematics 2007-05-23 V. A. Buslov

Gurski and Wanke showed that a graph class C has bounded tree-width if and only if its associated class of directed line graphs has bounded clique-width. Inevitably -- asking whether this relationship lifts to directed graphs -- we…

Combinatorics · Mathematics 2025-02-24 Benjamin Merlin Bumpus , Kitty Meeks , William Pettersson

Transfinite graphs have been defined and examined in a variety of prior works, but transfinite digraphs had not as yet been investigated. The present work embarks upon such a task. As with the ordinals, transfinite digraphs appear in a…

Combinatorics · Mathematics 2009-04-28 A. H. Zemanian

Rank-width is a width parameter of graphs describing whether it is possible to decompose a graph into a tree-like structure by `simple' cuts. This survey aims to summarize known algorithmic and structural results on rank-width of graphs.

Combinatorics · Mathematics 2018-05-16 Sang-il Oum

An oriented graph $G^\sigma$ is a digraph without loops or multiple arcs whose underlying graph is $G$. Let $S\left(G^\sigma\right)$ be the skew-adjacency matrix of $G^\sigma$ and $\alpha(G)$ be the independence number of $G$. The rank of…

Combinatorics · Mathematics 2017-04-25 J. Huang , S. C. Li , H. Wang

We construct and study a class of algebras associated to generalized layered graphs, i.e. directed graphs with a ranking function on their vertices. Each finite directed acyclic graph admits countably many structures of a generalized…

Combinatorics · Mathematics 2008-06-11 Vladimir Retakh , Robert Lee Wilson

Constructions of directed configuration graphs based on a given bi-degree distribution were introduced in random graph theory some years ago. These constructions lead to graphs where the degrees of two nodes belonging to the same edge are…

Probability · Mathematics 2017-01-13 Philippe Deprez , Mario V. Wüthrich

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

A metric graph is a geometric realization of a finite graph by identifying each edge with a real interval. A divisor on a metric graph $\Gamma$ is an element of the free abelian group on $\Gamma$. The rank of a divisor on a metric graph is…

Combinatorics · Mathematics 2013-05-01 Ye Luo

A k-digraph is an orientation of a multi-graph that is without loops and contains at most k edges between any pair of distinct vertices. We obtain necessary and sufficient conditions for a sequence of non-negative integers in non-decreasing…

Combinatorics · Mathematics 2007-05-23 S. Pirzada , U. Samee

We study the algebraic rank of a divisor on a graph, an invariant defined using divisors on algebraic curves dual to the graph. We prove it satisfies the Riemann-Roch formula, a specialization property, and the Clifford inequality. We prove…

Algebraic Geometry · Mathematics 2014-11-26 Lucia Caporaso , Yoav Len , Margarida Melo

The rank of a graph is defined to be the rank of its adjacency matrix. A graph is called reduced if it has no isolated vertices and no two vertices with the same set of neighbors. A reduced graph $G$ is said to be maximal if any reduced…

Combinatorics · Mathematics 2020-10-09 H. Esmailian , E. Ghorbani , S. Hossein Ghorban , G. B. Khosrovshahi

We study varieties that contain unranked tree languages over all alphabets. Trees are labeled with symbols from two alphabets, an unranked operator alphabet and an alphabet used for leaves only. Syntactic algebras of unranked tree languages…

Formal Languages and Automata Theory · Computer Science 2015-10-27 Magnus Steinby , Eija Jurvanen , Antonio Cano

For a weighted digraph without loops $V$, the arc weights of which can be obtained from an undirected graph with loops ${\sf P}$ according to the rule $v_{ij}=p_{ij}-p_{ii}$, the properties are studied. An effective algorithm for…

Combinatorics · Mathematics 2025-04-22 Vasily Buslov

Link directions are essential to the functionality of networks and their prediction is helpful towards a better knowledge of directed networks from incomplete real-world data. We study the problem of predicting the directions of some links…

Physics and Society · Physics 2013-07-16 Fangjian Guo , Zimo Yang , Tao Zhou

We study the rank weight hierarchy of linear codes which are stable under a linear endomorphism defined over the base field, in particular when the endomorphism is cyclic. In this last case, we give a necessary and sufficient condition for…

Information Theory · Computer Science 2026-02-02 G. Berhuy , J. Molina

A $k$-ranking of a graph $G$ is a labeling of its vertices from $\{1,\ldots,k\}$ such that any nontrivial path whose endpoints have the same label contains a larger label. The least $k$ for which $G$ has a $k$-ranking is the ranking number…

Combinatorics · Mathematics 2014-01-14 Daniel C. McDonald

A weighted (directed) graph is a (directed) graph with integer weights assigned to its vertices and edges. The weight of a subgraph is the sum of weights of vertices and edges in the subgraph. The problem of determining the largest order…

Combinatorics · Mathematics 2024-07-02 Ajit A. Diwan

An oriented graph $G^\sigma$ is a digraph without loops and multiple arcs, where $G$ is called the underlying graph of $G^\sigma$. Let $S(G^\sigma)$ denote the skew-adjacency matrix of $G^\sigma$. The rank of the skew-adjacency matrix of…

Combinatorics · Mathematics 2014-04-30 Xueliang Li , Guihai Yu