1.3. TopologyProgramme leader: J. van Mill
Description of the programme.
The programme focuses on the study of the topology of classical objects, like the Hilbert cube, continua in the plane which arise in topological dynamics, various topological groups and the Cech-Stone compactifications of the reals and the integers, as well as more recent objects like certain compact L-spaces, spaces of chaotic maps and "nice" two-point sets in the plane. Most of these objects are studied using methods from several branches of general and geometric topology, as well as non-topological methods, most notably from functional analysis, measure theory, set theory and geometry. The topological methods can be as diverse as infinite-dimensional topology, descriptive set theory, continuum theory and the theory of ultrafilters. A good illustration of the kind of interaction one gets is provided by the study of so-called colourings of maps, related to the question whether a fixed-point-free selfmap f on X extends to a fixed-point-free selfmap on the Cech-Stone compactification of X.
Here one meets classical results from algebraic and geometric topology, like the Ljusternik-Schnirelman theorem and the Borsuk-Ulam theorem, non-trivial results in topological groups, methods from dimension theory and topological dynamics, as well as set-theoretic methods to construct counterexamples.
This theory also gives rise to applications in the form of fixed point theorems, for instance.
Of course similar things can be said for other specific research interests within this programme.