We hold seminar on Tuesday, June 19,
time 16:00-17:30, seminar room: 201.
Speaker: Nadav Meir(BGU)
Title: Symmetric indivisibility – not what you expect.
An L-structure M is indivisible if for every colouring of M in two colours there is a monochromatic substructure M’ isomorphic to M.
An L-structure M’ is symmetrically indivisible if, in addition, M’ is symmetrically embedded in M (that is every automorphism of M’ can be expanded to an automorphism of M.
Hasson, Kojman and Onshuus asked in their article “is there a symmetrically indivisible structure with a reduct not symmetrically indivisible?”
We show that the answer is yes, and in general symmetric indivisible is not what one would expect.