Monopole Floer Homology and Real Structures

We define a “real” version of Kronheimer-Mrowka’s monopole Floer homology for a 3-manifold equipped with an involution. As a special case, we obtain invariants for links via their double branched covers. The new input is the notion of a real spin-c structure, which consists of a spin-c structure along with a compatible anti-linear involution on the spinor bundle.