All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Previous Page 11 Next

Displaying 201 – 220 of 299

Showing per page

Graphs for n-circular matroids

Renata Kawa (2010)

Discussiones Mathematicae Graph Theory

We give "if and only if" characterization of graphs with the following property: given n ≥ 3, edges of such graphs form matroids with circuits from the collection of all graphs with n fundamental cycles. In this way we refer to the notion of matroidal family defined by Simões-Pereira [2].

Graphs having no quantum symmetry

Teodor Banica, Julien Bichon, Gaëtan Chenevier (2007)

Annales de l’institut Fourier

We consider circulant graphs having p vertices, with p prime. To any such graph we associate a certain number k , that we call type of the graph. We prove that for p ≫ k the graph has no quantum symmetry, in the sense that the quantum automorphism group reduces to the classical automorphism group.

Graphs isomorphic to their path graphs

Martin Knor, Ľudovít Niepel (2002)

Mathematica Bohemica

We prove that for every number n ≥ 1 , the n -iterated P 3 -path graph of G is isomorphic to G if and only if G is a collection of cycles, each of length at least 4. Hence, G is isomorphic to P 3 ( G ) if and only if G is a collection of cycles, each of length at least 4. Moreover, for k ≥ 4 we reduce the problem of characterizing graphs G such that P k ( G ) ≅ G to graphs without cycles of length exceeding k .

Graphs maximal with respect to hom-properties

Jan Kratochvíl, Peter Mihók, Gabriel Semanišin (1997)

Discussiones Mathematicae Graph Theory

For a simple graph H, →H denotes the class of all graphs that admit homomorphisms to H (such classes of graphs are called hom-properties). We investigate hom-properties from the point of view of the lattice of hereditary properties. In particular, we are interested in characterization of maximal graphs belonging to →H. We also provide a description of graphs maximal with respect to reducible hom-properties and determine the maximum number of edges of graphs belonging to →H.

Graphs S ( n , k ) and a variant of the Tower of Hanoi problem

Sandi Klavžar, Uroš Milutinović (1997)

Czechoslovak Mathematical Journal

For any n ≥ 1 and any k ≥ 1 , a graph S ( n , k ) is introduced. Vertices of S ( n , k ) are n -tuples over { 1 , 2 , ... , k } and two n -tuples are adjacent if they are in a certain relation. These graphs are graphs of a particular variant of the Tower of Hanoi problem. Namely, the graphs S ( n , 3 ) are isomorphic to the graphs of the Tower of Hanoi problem. It is proved that there are at most two shortest paths between any two vertices of S ( n , k ) . Together with a formula for the distance, this result is used to compute the distance between two vertices in...

Currently displaying 201 – 220 of 299