%0 Journal Article
%T Automorphisms and strongly invariant relations
%A Ferdinand B£¿rner
%A Martin Goldstern
%A Saharon Shelah
%J Mathematics
%D 2003
%I arXiv
%X We investigate characterizations of the Galois connection sInv-Aut between sets of finitary relations on a base set A and their automorphisms. In particular, for A=omega_1, we construct a countable set R of relations that is closed under all invariant operations on relations and under arbitray intersections, but is not closed under sInv(Aut(-)). Our structure (A,R) has an omega-categorical first order theory. A higher order definable well-order makes it rigid, but any reduct to a finite language is homogeneous.
%U http://arxiv.org/abs/math/0309165v1