Let a and b be integers 4 ≤ a ≤ b. We give simple, sufficient conditions for graphs to contain an even [a, b]-factor. The conditions are on the order and on the minimum degree, or on the edge-connectivity of the graph.

This work is devoted to contribute with two algorithms for performing, in an efficient way, connected components labeling and boundary extraction from orthogonal pseudo-polytopes. The proposals are specified in terms of the extreme vertices model in the n-dimensional space nDEVM . An overview of the model is presented, considering aspects such as its fundamentals and basic algorithms. The tempo...

We consider a stochastic graph generated by a time-continuous birth-death process. The vertices are the living particles, directed edges go from mothers to daughters. The size and the structure of the connected components are investigated. Furthermore, the number of connected components is determined.

The popularity of a pattern p in a set of permutations is the sum of the number of copies of p in each permutation of the set. We study pattern popularity in the set of 132-avoiding permutations. Two patterns are equipopular if, for all n, they have the same popularity in the set of length-n 132-avoiding permutations. There is a well-known bijection between 132-avoiding permutations and binary ...

The interpretation by Duskin and Glenn of abelian sheaf cohomology as connected components of a category of torsors is extended to homotopy classes. This is simultaneously an extension of Verdier’s version of Čech cohomology to homotopy.

We completely describe the structure of the connected components of transversals to a collection of n line segments in R. We show that n > 3 arbitrary line segments in R admit 0, 1, . . . , n or infinitely many line transversals. In the latter case, the transversals form up to n connected components.

The traditional parameter used as a measure of vulnerability of a network modeled by a graph with perfect nodes and edges that may fail is the edge connectivity λ. Of course , () p q K p λ = where p q ≤. In that case, failure of the network simply means that the surviving subgraph becomes disconnected upon the failure of individual edges. If, instead, failure of the network is defined to mean t...

In this paper, we study the density of fixed strongly connected subtournaments on 5 vertices in large tournaments. We determine the maximum density asymptotically for three tournaments as well as extremal families for each tournament. We use Razborov’s semidefinite method for flag algebras to prove the upper bounds.

Necessary and sufficient conditions on n and A are given for the existence an edge-disjoint decomposition of AKn into copies of the graph of a 3-dimensional cube. Also, necessary and sufficient conditions on m, nand>' are given for similar decompositions of >'Km,n'