6 research outputs found
Singular Ramsey and Turán numbers
We say that a subgraph F of a graph G is singular if the degrees dG(v) are all equal or all distinct for the vertices v ∈ V (F). The singular Ramsey number Rs(F) is the smallest positive integer n such that, for every m at least n, in every edge 2-coloring of Km, at least one of the color classes contains F as a singular subgraph. In a similar flavor, the singular Turán number Ts(n,F) is defined as the maximum number of edges in a graph of order n, which does not contain F as a singular subgraph. In this paper we initiate the study of these extremal problems. We develop methods to estimate Rs(F) and Ts(n,F), present tight asymptotic bounds and exact results
The Total Irregularity of Graphs under Graph Operations
The total irregularity of a graph is defined as \irr_t(G)=1/2 \sum_{u,v
\in V(G)} , where denotes the degree of a vertex . In this paper we give (sharp) upper bounds on the total irregularity
of graphs under several graph operations including join, lexicographic product,
Cartesian product, strong product, direct product, corona product, disjunction
and symmetric difference.Comment: 14 pages, 3 figures, Journal numbe