Results 101 to 110 of about 16,499 (231)
On Tight Tree‐Complete Hypergraph Ramsey Numbers
Journal of Graph Theory, Volume 113, Issue 1, Page 88-96, September 2026.ABSTRACT Chvátal showed that for any tree T with k edges, the Ramsey number R ( T , n ) = k ( n − 1 ) + 1. For r = 3 or 4, we show that, if T is an r‐uniform nontrivial tight tree, then the hypergraph Ramsey number R ( T , n ) = Θ ( n r − 1 ). The 3‐uniform result comes from observing a construction of Cooper and Mubayi.
Jiaxi Nie
wiley +1 more source
MathematicsTheenergy of a graph is a classical spectral invariant defined as the sum of the absolute values of the eigenvalues of its adjacency matrix. Recently, the notion of local energy was introduced to measure the contribution of vertices to the total energy ...
Carlos Espinal, Juan Rada
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Orientations of Graphs With at Most One Directed Path Between Every Pair of Vertices
Journal of Graph Theory, Volume 113, Issue 1, Page 143-164, September 2026.ABSTRACT Given a graph G, we say that an orientation D of G is a KT orientation if, for all u , v ∈ V ( D ), there is at most one directed path (in any direction) between u and v. Graphs that admit such orientations have been used to construct graphs with large chromatic number and small clique number that served as counterexamples to various ...
Barbora Dohnalová +3 more
wiley +1 more source
Discrete Mathematics, 1997 ``This paper focuses on a family of vertex symmetric digraphs \dots which were introduced by \textit{M. L. Fiol} [The relation between digraphs and groups through Cayley digraphs, Universitat Autònoma de Barcelona, 1984 (in Catalan)].'' For integers \(k\) and \(n\), \(1\leq k\leq n-1\), a digraph \(P(n,k)\) has as vertices the \(k\)-permutations of ...
Josep M. Brunat +2 more
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Akram B. Attar EXTENSIBILITY OF GRAPHS
مجلة علوم ذي قار, 2019 In this paper, the concepts of extension of a graph(digraph) and the extensible class of graphs(digraphs) have been introduced. The class of connected graphs as well as the class of Hamiltonian graphs which are extensible classes have also been proved ...
Akram Attar
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Spanish‐Speaking Secondary Students Reading and Spelling in English as a Foreign Language
European Journal of Education, Volume 61, Issue 3, September 2026.ABSTRACT Proficiency in English reading and spelling is essential, as many professional environments require both spoken and written skills. Literacy development in English as a foreign language poses challenges for learners whose first language is transparent, such as Spanish, due to the complexity and inconsistency of English orthography.
Paz Suárez‐Coalla +3 more
wiley +1 more source
Upper Bounds on the Minimum Size of Feedback Arc Set of Directed Multigraphs With Bounded Degree
Journal of Graph Theory, Volume 112, Issue 4, Page 421-432, August 2026.ABSTRACT An oriented multigraph is a directed multigraph without directed 2‐cycles. Let fas ( D ) denote the minimum size of a feedback arc set in an oriented multigraph D. In several papers, upper bounds for fas ( D ) were obtained for oriented multigraphs D with maximum degree upper‐bounded by a constant.
Gregory Gutin +3 more
wiley +1 more source
Discrete Mathematics, 2006 Let $Φ(x,y)$ be a bivariate polynomial with complex coefficients. The zeroes of $Φ(x,y)$ are given a combinatorial structure by considering them as arcs of a directed graph $G(Φ)$. This paper studies some relationship between the polynomial $Φ(x,y)$ and the structure of $G(Φ)$.
Josep M. Brunat, Antonio Montes
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Circulant Digraphs with Larger Linear Guessing Number and Smaller Degree
MathematicsThe guessing number of a digraph is a new invariant in graph theory raised by S. Riis in 2006 and based on its applications in network coding and boolean circuit complexity theory. In this paper, we present the lower and upper bounds on a guessing number
Aixian Zhang, Keqin Feng
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On a Ramsey–Turán variant of Roth's theorem
Bulletin of the London Mathematical Society, Volume 58, Issue 8, August 2026.Abstract A classical theorem of Roth states that the maximum size of a solution‐free set of a homogeneous linear equation L$\mathcal {L}$ in Fp$\mathbb {F}_p$ is o(p)$o(p)$ if and only if the sum of the coefficients of L$\mathcal {L}$ is 0. In this paper, we prove a Ramsey–Turán variant of Roth's theorem, with respect to a natural notion of “structured”
Matija Bucić +4 more
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