Understanding the dark sector of the universe is one of the most challenging problems in current cosmology, and gravitational lensing is among the principaltoolstoinvestigateit. Iamatheoretical astrophysicist interested in the mathematical theory of lensing, as well as in general relativity and its modifications. Recently, I studied the origin of certain magnification invariants underlying the flux-ratio anomaly with Lefschetz fixed point theory, and the Randers-Finsler structure of the Kerr optical geometry. Joining IPMU from the Mathematics Department of Duke University, I hope to create some more links between the mathematics and astronomy communities here.