Strongly regular graphs: Values of and for which there are only finitely many feasible .
Structures ofW(2.2) Lie conformal algebra
The purpose of this paper is to study W(2, 2) Lie conformal algebra, which has a free ℂ[∂]-basis L, M such that [...] [LλL]=(∂+2λ)L,[LλM]=(∂+2λ)M,[MλM]=0 . In this paper, we study conformal derivations, central extensions and conformal modules for this Lie conformal algebra. Also, we compute the cohomology of this Lie conformal algebra with coefficients in its modules. In particular, we determine its cohomology with trivial coefficients both for the basic and reduced complexes.
Subdominant eigenvalues for stochastic matrices with given column sums.
Sudoku graphs are integral.
Sufficient conditions on the existence of factors in graphs involving minimum degree
For a set of graphs, an -factor of a graph is a spanning subgraph of , where each component of is contained in . It is very interesting to investigate the existence of factors in a graph with given minimum degree from the prospective of eigenvalues. We first propose a tight sufficient condition in terms of the -spectral radius for a graph involving minimum degree to contain a star factor. Moreover, we also present tight sufficient conditions based on the -spectral radius and the distance...
Survey of spectra of Laplacians on finite symmetric spaces.
Tetracyclic harmonic graphs
The algebraic connectivity of two trees connected by an edge of infinite weight.
The alternating sign matrix polytope.
The characteristic polynomial of a graph is reconstructible from the characteristic polynomials of its vertex-deleted subgraphs and their complements.
The classification of edges and the change in multiplicity of an eigenvalue of a real symmetric matrix resulting from the change in an edge value
We take as given a real symmetric matrix A, whose graph is a tree T, and the eigenvalues of A, with their multiplicities. Each edge of T may then be classified in one of four categories, based upon the change in multiplicity of a particular eigenvalue, when the edge is removed (i.e. the corresponding entry of A is replaced by 0).We show a necessary and suficient condition for each possible classification of an edge. A special relationship is observed among 2-Parter edges, Parter edges and singly...
The classification of finite groups by using iteration digraphs
A digraph is associated with a finite group by utilizing the power map defined by for all , where is a fixed natural number. It is denoted by . In this paper, the generalized quaternion and -groups are studied. The height structure is discussed for the generalized quaternion. The necessary and sufficient conditions on a power digraph of a -group are determined for a -group to be a generalized quaternion group. Further, the classification of two generated -groups as abelian or non-abelian...
The combinatorial structure of eventually nonnegative matrices.
The complete product of annihilatingly unique digraphs.
The diameter and Laplacian eigenvalues of directed graphs.
The distance matrix of a bidirected tree.
The enumeration of bit-sequences that satisfy local criteria.
The Estrada Index
The Estrada Index: An Updated Survey
The Euler characteristic of a category.