Title: Automorphism groups of treelike objects.

 

Abstract. A transitive permutation group G on a set X is a Jordan group if there is a subset A of X with |A|>1 such that the pointwise stabiliser in G of the complement of A is transitive on A (plus a technical condition that if G is k-transitive on X then |X-A|>k-1). I will review the structure theory of Jordan groups, but mainly focus on a construction in the PhD thesis of Asma Almazaydeh of a certain treeline Fraisse limit whose automorphism group is a Jordan group.

 

We will meet for coffee at 3:15pm in the Huxley 5th floor common room.