Automorphisms of the Rado meet-tree
We prove that the group of automorphisms of the generic meet-tree expansion of an infinite non-unary free Fra\"ıssé limit over a finite relational language is simple. As a prototypical case, the group of automorphism of the Rado meet-tree (i.e. the Fra\"ıssé limit of finite graphs which are also meet-trees) is simple.
math.LO↗