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C 55 -groups.

Dolfi, Silvio, Jabara, Enrico, Lucido, Maria Silvia (2004)

Sibirskij Matematicheskij Zhurnal

Canonical characters on simple graphs

Tanja Stojadinović (2013)

Czechoslovak Mathematical Journal

A multiplicative functional on a graded connected Hopf algebra is called the character. Every character decomposes uniquely as a product of an even character and an odd character. We apply the character theory of combinatorial Hopf algebras to the Hopf algebra of simple graphs. We derive explicit formulas for the canonical characters on simple graphs in terms of coefficients of the chromatic symmetric function of a graph and of canonical characters on quasi-symmetric functions. These formulas and...

Cayley color graphs of inverse semigroups and groupoids

Nándor Sieben (2008)

Czechoslovak Mathematical Journal

The notion of Cayley color graphs of groups is generalized to inverse semigroups and groupoids. The set of partial automorphisms of the Cayley color graph of an inverse semigroup or a groupoid is isomorphic to the original inverse semigroup or groupoid. The groupoid of color permuting partial automorphisms of the Cayley color graph of a transitive groupoid is isomorphic to the original groupoid.

Characterization by intersection graph of some families of finite nonsimple groups

Hossein Shahsavari, Behrooz Khosravi (2021)

Czechoslovak Mathematical Journal

For a finite group G , Γ ( G ) , the intersection graph of G , is a simple graph whose vertices are all nontrivial proper subgroups of G and two distinct vertices H and K are adjacent when H K 1 . In this paper, we classify all finite nonsimple groups whose intersection graphs have a leaf and also we discuss the characterizability of them using their intersection graphs.

Classification of rings with toroidal Jacobson graph

Krishnan Selvakumar, Manoharan Subajini (2016)

Czechoslovak Mathematical Journal

Let R be a commutative ring with nonzero identity and J ( R ) the Jacobson radical of R . The Jacobson graph of R , denoted by 𝔍 R , is defined as the graph with vertex set R J ( R ) such that two distinct vertices x and y are adjacent if and only if 1 - x y is not a unit of R . The genus of a simple graph G is the smallest nonnegative integer n such that G can be embedded into an orientable surface S n . In this paper, we investigate the genus number of the compact Riemann surface in which 𝔍 R can be embedded and explicitly...

Color Energy Of A Unitary Cayley Graph

Chandrashekar Adiga, E. Sampathkumar, M.A. Sriraj (2014)

Discussiones Mathematicae Graph Theory

Let G be a vertex colored graph. The minimum number χ(G) of colors needed for coloring of a graph G is called the chromatic number. Recently, Adiga et al. [1] have introduced the concept of color energy of a graph Ec(G) and computed the color energy of few families of graphs with χ(G) colors. In this paper we derive explicit formulas for the color energies of the unitary Cayley graph Xn, the complement of the colored unitary Cayley graph (Xn)c and some gcd-graphs.

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