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Fundamental Groupoids for Graphs [PDF]

open access: yesCategories and General Algebraic Structures with Applications, 2022
In recent years several notions of discrete homotopy for graphs have been introduced, including a notion of ×-homotopy due to Dochtermann. In this paper, we define a ×-homotopy fundamental groupoid for graphs, and prove that it is a functorial ×-homotopy
Tien Chih, Laura Scull
doaj   +1 more source

Spatio–Spectral Limiting on Replacements of Tori by Cubes

open access: yesMathematics, 2023
A class of graphs is defined in which each vertex of a discrete torus is replaced by a Boolean hypercube in such a way that vertices in a fixed subset of each replacement cube are adjacent to corresponding vertices of a neighboring replacement cube ...
Jeffrey A. Hogan, Joseph D. Lakey
doaj   +1 more source

Identification Conditions for the Solvability of NP-complete Problems for the Class of Pre-fractal Graphs

open access: yesМоделирование и анализ информационных систем, 2021
Modern network systems (unmanned aerial vehicles groups, social networks, network production chains, transport and logistics networks, communication networks, cryptocurrency networks) are distinguished by their multi-element nature and the dynamics of ...
Aleksandr Vasil'evich Tymoshenko   +2 more
doaj   +1 more source

Not all planar graphs are in PURE-4-DIR

open access: yesJournal of Graph Algorithms and Applications, 2020
We prove that some planar graphs are not intersection graphs of segments if only four slopes are allowed for the segments, and if parallel segments do not intersect. This refutes a conjecture of D. West [D. West, SIAM J. Discrete Math. Newsletter, 1991].
Daniel Gonçalves
doaj   +1 more source

Discrete Random Walks on One-Sided ``Periodic'' Graphs [PDF]

open access: yesDiscrete Mathematics & Theoretical Computer Science, 2003
In this paper we consider discrete random walks on infinite graphs that are generated by copying and shifting one finite (strongly connected) graph into one direction and connecting successive copies always in the same way.
Michael Drmota
doaj   +1 more source

Discrete Integral and Discrete Derivative on Graphs and Switch Problem of Trees

open access: yesMathematics, 2023
For a vertex and edge weighted (VEW) graph G with a vertex weight function fG let Wα,β(G)=∑{u,v}⊆V(G)[αfG(u)×fG(v)+β(fG(u)+fG(v))]dG(u,v) where, α,β∈ℝ and dG(u,v) denotes the distance, the minimum sum of edge weights across all the paths connecting u,v∈V(
M. H. Khalifeh, Abdol-Hossein Esfahanian
doaj   +1 more source

On the Inverse Symmetric Division Deg Index of Unicyclic Graphs

open access: yesComputation, 2022
The symmetric division deg (SDD) index is among the 148 discrete Adriatic indices that were developed about a decade ago. Motivated by the success of the SDD index, Ghorbani et al.
Abeer M. Albalahi, Akbar Ali
doaj   +1 more source

Cryptanalysing the critical group: efficiently solving Biggs's discrete logarithm problem

open access: yesJournal of Mathematical Cryptology, 2009
Biggs has recently proposed the critical group of a certain class of finite graphs as a platform group for cryptosystems relying on the difficulty of the discrete log problem. The paper uses techniques from the theory of Picard groups on finite graphs to
Blackburn Simon R.
doaj   +1 more source

Crossing Numbers of Join Product with Discrete Graphs: A Study on 6-Vertex Graphs

open access: yesMathematics, 2023
Reducing the number of crossings on graph edges can be useful in various applications, including network visualization, circuit design, graph theory, cartography or social choice theory.
Jana Fortes, Michal Staš
doaj   +1 more source

Remarks on Dynamic Monopolies with Given Average Thresholds

open access: yesDiscussiones Mathematicae Graph Theory, 2015
Dynamic monopolies in graphs have been studied as a model for spreading processes within networks. Together with their dual notion, the generalized degenerate sets, they form the immediate generalization of the classical notions of vertex covers and ...
Centeno Carmen C., Rautenbach Dieter
doaj   +1 more source

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