Seiberg-Witten invariants (a minicourse, 8 lectures) Seiberg-Witten invariants are one of the most powerful tools in 4-dimensional topology and symplectic geometry. I would give a self-contained introduction to basic properties of Seiberg-Witten invariants of 4-dimensional manifolds. I will introduce the Clifford algebras, explain the Bott periodicity for Clifford algebras, define the $Spin$ and $Spin^c$-structures, the Seiberg-Witten equation, the Weitzenbock formula, explain the compactness of the space of solutions of the Seiberg-Witten equation, and compute the Seiberg-Witten invariants of Kahler surfaces. Site of the mini-course: http://verbit.ru/IMPA/SW-2026 Literature: Lawson, H. B., Michelsohn, M.-L., Spin Geometry (1989) John W. Morgan, The Seiberg-Witten Equations and Applications to the Topology of Smooth Four-Manifolds (1995) Liviu I. Nicolaescu, Notes on Seiberg-Witten Theory Graduate Studies in Mathematics, Vol. 28, (2000) https://www3.nd.edu/~lnicolae/swnotes.pdf Michael Hutchings and Clifford Henry Taubes, An introduction to the Seiberg-Witten equations on symplectic manifolds http://math.berkeley.edu/~hutching/pub/tn.pdf