This working group is organized as one of a series of working groups
organized by DIMACS (Rutgers University, New Jersey, USA), DIMATIA (Prague), and the Rényi
Institute (Budapest). This working group is mainly for the members of the
organizing institutions, but every interested mathematician is welcome.
Fred Roberts will participate in the beginning.
We will try to focus on the subject given in the title, but any related
lecture is welcome.