Given a pair of analytic equivalence relations E and F, we determine under which conditions it is possible to find an Lω1,ω-elementary class C such that E and F are Borel equivalent to, respectively, isomorphism and bi- embeddability on C: quite surprisingly, it turns out that, apart from the obvious limitations, such an elementary class always exists. This result gives an (almost complete) answer to previous questions of Louveau-Rosendal (2005) and Friedman-Motto Ros (2009).
On the complexity of the relations of isomorphism and bi-embeddability
28.01.2010 15:00 - 16:30
Organiser:
KGRC
Location:
SR 101, 2. St., Währinger Str. 25