A remark on systems of maximal cliques of a graph
A remark on the (2,2)-domination number
A subset D of the vertex set of a graph G is a (k,p)-dominating set if every vertex v ∈ V(G)∖D is within distance k to at least p vertices in D. The parameter denotes the minimum cardinality of a (k,p)-dominating set of G. In 1994, Bean, Henning and Swart posed the conjecture that for any graph G with δₖ(G) ≥ k+p-1, where the latter means that every vertex is within distance k to at least k+p-1 vertices other than itself. In 2005, Fischermann and Volkmann confirmed this conjecture for all integers...
A remark on -regular orthomodular lattices
A finite orthomodular lattice in which every maximal Boolean subalgebra (block) has the same cardinality is called -regular, if each atom is a member of just blocks. We estimate the minimal number of blocks of -regular orthomodular lattices to be lower than of equal to regardless of .
A reminiscence about shortest spanning subtrees
A representation of Sheffer polynomials in terms of a differential equation for their generating functions.
A representation of Sheffer polynomials in terms of a differential equation for their generating functions. (Short Communication).
A restricted random walk defined via a Fibonacci process.
A result on co-chromatic graphs.
A result on -critical graphs.
A result related to the largest eigenvalue of a tree
In this note we prove that {0,1,√2,√3,2} is the set of all real numbers l such that the following holds: every tree having an eigenvalue which is larger than l has a subtree whose largest eigenvalue is l.
A Riordan array proof of a curious identity.
A Schröder generalization of Haglund's statistic on Catalan paths.
A semigroup approach to wreath-product extensions of Solomon's descent algebras.
A Sequence of Exponential Numbers
A series transformation formula and related polynomials.
A service points location problem with Min-Max distance optimality criterion
A sextuple product identity with applications.
A sharp bound for the reconstruction of partitions.
A sharp inequality involving the psi function.
A sharp upper bound for the spectral radius of a nonnegative matrix and applications
We obtain a sharp upper bound for the spectral radius of a nonnegative matrix. This result is used to present upper bounds for the adjacency spectral radius, the Laplacian spectral radius, the signless Laplacian spectral radius, the distance spectral radius, the distance Laplacian spectral radius, the distance signless Laplacian spectral radius of an undirected graph or a digraph. These results are new or generalize some known results.