This lecture, presented by Immanuel Van Santen from Universität Basel, discusses the complement problem for hypersurfaces in projective spaces. The main focus is on determining if two hypersurfaces are isomorphic based on their complements. The talk explores counterexamples for various cases and provides partial affirmative answers. Additionally, it delves into the isomorphism of rational normal projective surfaces and their coincidence in the Grothendieck ring.