Title: An index theorem for end-periodic operators

Abstract: We extend the Atiyah, Patodi, and Singer index theorem for Dirac type operators from the context of 
manifolds with cylindrical ends to that of manifolds with periodic ends. Our theorem provides a natural complement 
to Taubes' Fredholm theory for general end-periodic operators. It expresses the index in terms of a new 
end-periodic eta-invariant which equals the Atiyah-Patodi-Singer eta-invariant in the cylindrical setting. This is 
a joint project with Tom Mrowka and Daniel Ruberman.