Title: Doubled Khovanov Homology,
Abstract: We define a homology theory of virtual links built out of the direct sum of
the standard Khovanov complex with itself, motivating the name doubled Khovanov
homology. We demonstrate that it can be used to show that some virtual links
are non-classical, and that it yields a condition on a virtual knot being the
connect sum of two unknots. Further, we show that doubled Khovanov homology
possesses a perturbation analogous to that defined by Lee in the classical case
and define a doubled Rasmussen invariant. This invariant is used to obtain
various cobordism obstructions; in particular it is an obstruction to
sliceness. Finally, we show that the doubled Rasmussen invariant contains the
odd writhe of a virtual knot, and use this to show that knots with non-zero odd
writhe are not slice.