Speaker：Prof. JIANG Tao Miami University
Time：20160520 16:3017:30
Place:1518
Detail： Given family L of graphs, the Turan number
ex(n,L) is defined to be the maximum number of edges in an nvertex graph
which does not contain any member of L as a subgraph. In this talk, we
study the Turan number of the family of the graphs with average degree
at least d and order at most t (denoted by F_{d,t}) (d\geq 2). The
case d=2 is equivalent tothe wellknown girth problem. For ex(n, F_{d,t}),
Random graphs give a lower bound on the order \Omega(n^{22/d). We give an
almost matching upper bound of O(n^{22/d+c_{d,t}}) where c_{d,t} goes to 0 for
fixed d as t goes to infinity . This partially answers a question of Verstraete.
