Logic Colloquium 2008
Todor Tsankov Positive definite functions on equivalence relations
We consider positive definite functions on countable equivalence relations, in particular ones arising from subequivalence relations. We discuss various applications, including ones to a recent co-inducing construction of Epstein and orbit equivalence as well as percolation on Cayley graphs of property (T) groups. This is joint work with A. Ioana and A. Kechris.