Results 171 to 180 of about 1,408,918 (247)

Catalan Bounds for Symmetric Strength‐Two Orthogonal Arrays

open access: yesJournal of Combinatorial Designs, EarlyView.
ABSTRACT A Hamming shell construction is a two‐level array obtained by taking every binary vector of a given Hamming weight a prescribed number of times, for each weight in turn. Such arrays are invariant under all permutations of the factors, and they are strength‐two orthogonal arrays exactly when the multiplicities satisfy three linear constraints ...
Ruwan C. Karunanayaka
wiley   +1 more source

Density Conditions for k $k$ Vertex‐Disjoint Triangles in Tripartite Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Let n , k $n,k$ be positive integers such that n ≥ k $n\ge k$ and G $G$ be a tripartite graph with parts A , B , C $A,B,C$ such that ∣ A ∣ = ∣ B ∣ = ∣ C ∣ = n $| A| =| B| =| C| =n$. Denote the edge densities of G [ A , B ] , G [ A , C ] $G[A,B],G[A,C]$ and G [ B , C ] $G[B,C]$ by α , β $\alpha ,\beta $ and γ $\gamma $, respectively.
Mingyang Guo, Klas Markström
wiley   +1 more source

Chromatic Ramsey Numbers and Two‐Color Turán Densities

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Given a graph G, its 2‐color Turán number ex ( 2 ) ( n , G ) is the maximum number of edges in an n‐vertex graph, such that the edges can be colored with two colors avoiding a monochromatic copy of G. Let π ( 2 ) ( G ) = lim n → ∞ ex ( 2 ) ( n , G ) / n 2 be the 2‐color Turán density of G.
Maria Axenovich, Simon Gaa, Dingyuan Liu
wiley   +1 more source

Tree Independence Number III. Thetas, Prisms and Stars

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT We prove that for every t ∈ N $t\in {\mathbb{N}}$ there exists τ = τ ( t ) ∈ N $\tau =\tau (t)\in {\mathbb{N}}$ such that every (theta, prism, K 1 , t ${K}_{1,t}$)‐free graph has tree independence number at most τ $\tau $ (where we allow “prisms” to have one path of length zero).
Maria Chudnovsky   +2 more
wiley   +1 more source

On Odd Covers of Cliques and Disjoint Unions

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT Babai and Frankl posed the “odd cover problem” of finding the minimum cardinality of a collection of complete bipartite graphs such that every edge of the complete graph of order n $n$ is covered an odd number of times. In a previous paper with O'Neill, some of the authors proved that this value is always ⌈ n / 2 ⌉ $\lceil n/2\rceil $ or ⌈ n /
Calum Buchanan   +7 more
wiley   +1 more source

On Quantum Ergodicity for Higher Dimensional Cat Maps. [PDF]

open access: yesCommun Math Phys
Kurlberg P   +3 more
europepmc   +1 more source

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