Graphs without minor complete subgraphs

Extremal Graphs without Topological Complete Subgraphs

Complete subgraphs in multipartite graphs

Turán’s Theorem states that every graphG of edge density ‖G‖/ (|G| 2 ) > k−2 k−1 contains a complete graph K and describes the unique extremal graphs. We give a similar Theorem for `-partite graphs. For large `, we find the minimal edge density d` , such that every `-partite graph whose parts have pairwise edge density greater than d` contains a K . It turns out that d` = k−2 k−1 for large enou...

Complete subgraphs of random graphs

A classical theorem by Erdős, Kleitman and Rothschild on the structure of triangle-free graphs states that with high probability such graphs are bipartite. Our first main result refines this theorem by investigating the structure of the ’few’ triangle-free graphs which are not bipartite. We prove that with high probability these graphs are bipartite up to a few vertices. Similar results hold if...

optimal orientations of subgraphs of complete bipartite graphs

for a graph g, let d(g) be the set of all strong orientations of g. the orientationnumber of g is min {d(d) |d belongs to d(g)}, where d(d) denotes the diameterof the digraph d. in this paper, we determine the orientation number for some subgraphs of complete bipartite graphs.

Complete Subgraphs of Chromatic Graphs and Hypergraphs

In this note we consider k-chromatic graphs with given colour k r-graphs have vertex sets u C i , and no r-tuple (i .e. edge o f 1 the r-graph) has two vertices in the same colour class C i .