Abstract.

Non-crossing partitions have been introduced into combinatorial
mathematics by Kreweras 1972. These have been embedded into the
framework of reflection groups by Bessis and by Brady and Watt
around 2000. Armstrong extended their definition to m-divisible
non-crossing partitions associated with a reflection group.
Numerous enumerative results are known about these objects,
including two cyclic sieving phenomena in the sense of Reiner,
Stanton and White.

Motivated by work of Buan, Reiten and Thomas, Christian Stump
defined "positive m-divisible non-crossing partitions" associated
with a reflection group. As it turns out, one can again derive
numerous enumerative results for these objects, among which
two cyclic sieving phenomena (the proof of the latter is not yet
complete).

In the talk I will explain what all this is about.

This is joint work with Christian Stump.