Results 101 to 110 of about 615,797 (257)

On n-skein isomorphisms of graphs

Journal of Combinatorial Theory, Series B, 1982
AbstractH. Whitney [Amer. J. Math. 54 (1932), 150–168] proved that edge isomorphisms between connected graphs with at least five vertices are induced by isomorphisms and that circuit isomorphisms between 3-connected graphs are induced by isomorphisms. R. Halin and H. A. Jung [J. London Math. Soc. 42 (1967), 254–256] generalized these results by showing
Robert L. Hemminger, Heinz Adolf Jung
openaire   +1 more source

Partial Steiner Triple Systems With an Almost Parallel Class Missing Any Given Point

Journal of Combinatorial Designs, EarlyView.
ABSTRACT We say that a hypergraph is factor critical if it has no 1‐factor but deletion of any vertex results in a hypergraph that has a 1‐factor. We show that any factor‐critical hypergraph of order n $n$ has at least n $n$ edges, and that for all integers k > 1 $k\gt 1$ and n > 1 $n\gt 1$ with n ≡ 1 ( mod k ) $n\equiv 1({\rm{mod}}\,k)$ there exists a
Darryn Bryant, Sara Davies, Jack Neubecker   +2 more
wiley   +1 more source

Isomorphism versus commensurability for a class of finitely presented groups

, 2014
We construct a class of finitely presented groups where the isomorphism problem is solvable but the commensurability problem is unsolvable. Conversely, we construct a class of finitely presented groups within which the commensurability problem is ...
Arzhantseva, Goulnara, Minasyan, Ashot, Lafont, Jean-Francois   +2 more
core   +1 more source

Two graph isomorphism polytopes [PDF]

, 2009
The convex hull ψn,n of certain (n!)2 tensors was considered recently in connection with graph isomorphism. We consider the convex hull ψn of the n! diagonals among these tensors. We show: 1. The polytope ψn is a face of ψn,n. 2.
Onn, Shmuel
core   +1 more source

Catalan Bounds for Symmetric Strength‐Two Orthogonal Arrays

Journal 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

Graph Theory Students’ Perceptions of Graph Isomorphism [PDF]

Iranian Journal of Educational Research
Objective: Graph isomorphism is a central topic in graph theory, yet students often struggle to grasp its underlying principles. This study aimed to explore students' perceptions of graph isomorphism and identify the conceptual metaphors they employ when
Ali Jafari, Majid Haghverdi, Abolfazl Tehranian   +2 more
doaj  

Graph Homomorphism Revisited for Graph Matching [PDF]

, 2010
In a variety of emerging applications one needs to decide whether a graph G matches another Gp, i.e., whether G has a topological structure similar to that of Gp. The traditional notions of graph homomorphism and isomorphism often fall short of capturing
Li, Jianzhong, Ma, Shuai, Fan, Wenfei; id_orcid, Wu, Yinghui, Wang, Hongzhi   +4 more
core  

On Odd Covers of Cliques and Disjoint Unions

Journal 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, Alexander Clifton, Eric Culver, Péter Frankl, Jiaxi Nie, Kenta Ozeki, Puck Rombach, Mei Yin   +7 more
wiley   +1 more source

NLC-2 graph recognition and isomorphism [PDF]

, 2007
International audienceNLC-width is a variant of clique-width with many application in graph algorithmic. This paper is devoted to graphs of NLC-width two.
Vincent Limouzy, Limouzy, Vincent, de Montgolfier, Fabien, Michaël Rao, Rao, Michael, Fabien de Montgolfier   +5 more
core   +1 more source

The Isomorphism between Graphs and their Adjoint Graphs [PDF]

Canadian Mathematical Bulletin, 1965
A graph G is defined as a set X = {x1, …, xn} of elements xi called vertices, and a collection Γ of (not necessarily distinct) unordered pairs of distinct vertices, called edges. An edge (xi, xj) is said to be incident to xi and xj which are its end-vertices.
openaire   +2 more sources