Séminaire du 1er février 2010, 14h00:
Thomas Feierl, Algorithms, INRIA Paris-Rocquencourt.
Lattice walks in a Weyl chamber of type B.
We consider lattice walks in $\R^k$ confined to the region $0<x_1<x_2...<x_k$
with fixed (but arbitrary) starting and end points. The walks are required
to be "reflectable", that is, we assume that the number of paths can be
counted using a reflection principle argument.
The main results are asymptotic formulas for the total number of walks of
length $n$ with either a fixed or a free end point for a general class of walks
as $n$ tends to infinity.
As applications, we find the asymptotics for the number of $k$-non-crossing
tangled diagrams on the set $\{1,2,...,n\}$ as $n$ tends to infinity,
and asymptotics for the number of $k$-vicious walkers subject to a wall
restriction
in the random turns model as well as in the lock step model.
Asymptotics for all of these objects were either known only for certain
special cases, or have only been partially determined or were completely
unknown.
Virginie Collette
Last modified: Mon Jan 4 17:25:58 CET 2010