Fri, 03 Dec 2010
14:30
14:30
DH 3rd floor SR
Tue, 16 Nov 2010
14:30 -
15:30
L3
Triangles in tripartite graphs
John Talbot
(UCL)
Abstract
How many triangles must a graph of density d contain? This old question due to Erdos was recently answered by Razborov, after many decades of progress by numerous authors.
We will consider the analogous question for tripartite graphs. Given a tripartite graph with prescribed edges densities between each
pair of classes how many triangles must it contain?
Tue, 20 Jan 2009
14:30 -
15:30
L3
Vertex Turan problems in the hypercube
John Talbot
(UCL)
Abstract
Let $Q_n=\{0,1\}^n$ be the $n$-dimensional hypercube. For $1\leq d \leq n$ and $F\subseteq Q_d$ we consider the question of how large $S\subseteq Q _n$ can be if every embedding $i:Q_d\to Q_n$ satisfies $i(F)\not\subseteq S$. We determine the asymptotic behaviour of the largest $F$-free subsets of $Q_n$ for a variety of $F$, in particular we generalise the sole non-trivial prior result in this area: $F=Q_2$ due to E.A. Kostochka. Many natural questions remain open. This is joint work with Robert Johnson.
Thu, 05 Mar 2009
16:30 -
17:30
Free surface flows in the presence of electric fields
Jean-Marc Vanden-Broeck
(UCL)
Abstract
GIBSON BUILDING COMMON ROOM 2ND FLOOR
(Coffee and Cakes in Gibson Meeting Room - opposite common room)
The effects of electric fields on nonlinear free surface flows are investigated. Both inviscid and Stokes flows are considered.
Fully nonlinear solutions are computed by boundary integral equation methods and weakly nonlinear solutions are obtained by using long wave asymptotics and lubrication theory. Effects of electric fields on the stability of the flows are discussed. In addition applications to coating flows are presented.
Tue, 28 Feb 2006
15:00
15:00
L3