Results 81 to 90 of about 34,455 (233)
European Journal of Combinatorics, 2018 In 1995, Stiebitz asked the following question: For any positive integers $s,t$, is there a finite integer $f(s,t)$ such that every digraph $D$ with minimum out-degree at least $f(s,t)$ admits a bipartition $(A, B)$ such that $A$ induces a subdigraph with minimum out-degree at least $s$ and $B$ induces a subdigraph with minimum out-degree at least $t$?
Jianliang Wu +3 more
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A systematic approach for identifying drivers of critical safety and establishing their hierarchy
The Canadian Journal of Chemical Engineering, Volume 103, Issue 10, Page 4628-4646, October 2025.Abstract Learning from incidents is a crucial step in preventing and mitigating adverse events. Incident databases offer valuable insights for safety management improvements by cause and contributing factors. However, extracting meaningful information from incident investigation reports poses a significant challenge. This study introduces a data‐driven
Mohammad Zaid Kamil +2 more
wiley +1 more source
Skew-signings of positive weighted digraphs
Arab Journal of Mathematical Sciences, 2018 An arc-weighted digraph is a pair (D , ω) where D is a digraph and ω is an arc-weight function that assigns to each arc u v of D a nonzero real number ω (u v) .
Kawtar Attas +2 more
doaj +1 more source
Simple DFS on the Complement of a Graph and on Partially Complemented Digraphs [PDF]
, 2013 A complementation operation on a vertex of a digraph changes all outgoing arcs into non-arcs, and outgoing non-arcs into arcs. A partially complemented digraph $\widetilde{G}$ is a digraph obtained from a sequence of vertex complement operations on $G ...
Joeris, Benson +3 more
core
Number of Subgraphs and Their Converses in Tournaments and New Digraph Polynomials
Journal of Graph Theory, Volume 110, Issue 2, Page 127-131, October 2025.ABSTRACT An oriented graph D is converse invariant if, for any tournament T, the number of copies of D in T is equal to that of its converse − D. El Sahili and Ghazo Hanna [J. Graph Theory 102 (2023), 684‐701] showed that any oriented graph D with maximum degree at most 2 is converse invariant. They proposed a question: Can we characterize all converse
Jiangdong Ai +4 more
wiley +1 more source
Frucht’s Theorem for the Digraph Factorial
Discussiones Mathematicae Graph Theory, 2013 To every graph (or digraph) A, there is an associated automorphism group Aut(A). Frucht’s theorem asserts the converse association; that for any finite group G there is a graph (or digraph) A for which Aut(A) ∼= G.
Hammack Richard H.
doaj +1 more source
From Subkautz Digraphs to Cyclic Kautz Digraphs [PDF]
Journal of Interconnection Networks, 2018 The Kautz digraphs K(d, ℓ) are a well-known family of dense digraphs, widely studied as a good model for interconnection networks. Closely related to these, the cyclic Kautz digraphs CK(d, ℓ) were recently introduced by Böhmová, Huemer and the author, and some of its distance-related parameters were fixed.
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On Endomorphism Universality of Sparse Graph Classes
Journal of Graph Theory, Volume 110, Issue 2, Page 223-244, October 2025.ABSTRACT We show that every commutative idempotent monoid (a.k.a. lattice) is the endomorphism monoid of a subcubic graph. This solves a problem of Babai and Pultr and the degree bound is best‐possible. On the other hand, we show that no class excluding a minor can have all commutative idempotent monoids among its endomorphism monoids. As a by‐product,
Kolja Knauer, Gil Puig i Surroca
wiley +1 more source
Discussiones Mathematicae Graph Theory, 2018 A digraph is called irregular if its distinct vertices have distinct degree pairs. An irregular digraph is called minimal (maximal) if the removal of any arc (addition of any new arc) results in a non-irregular digraph. It is easily seen that the minimum
Górska Joanna +4 more
doaj +1 more source
A Dichotomy Theorem for Γ‐Switchable H‐Colouring on m‐Edge‐Coloured Graphs
Journal of Graph Theory, Volume 110, Issue 2, Page 200-208, October 2025.ABSTRACT Let G be a graph in which each edge is assigned one of the colours 1 , 2 , … , m, and let Γ be a subgroup of S m. The operation of switching at a vertex x of G with respect to an element π of Γ permutes the colours of the edges incident with x according to π.
Richard Brewster +2 more
wiley +1 more source