A topological space $(X, T)$ with property $R$ is maximal $R$ (minimal $R$) if $T$ is a maximal (minimal) element in the set $R(X)$ of all topologies on the set $X ...

The inverse degree of a graph G with no isolated vertices is defined as the sum of reciprocal of vertex degrees of the graph G. In this paper, we obtain several lower and upper bounds on inverse ...

In mathematics and computer science, a directed acyclic graph, is a finite directed graph with no directed cycles. It consists of finitely many vertices and edges, with each edge directed from one ...