Complements of connected hypersurfaces in S4S4
Abstract
Let XX and YY be the complementary regions of a closed hypersurface MM in S4=X∪MYS4=X∪MY. We use the Massey product structure in H∗(M;ℤ) to limit the possibilities for χ(X) and χ(Y). We show also that if π1(X)≠1 then it may be modified by a 2-knot satellite construction, while if χ(X)≤1 and π1(X) is abelian then β1(M)≤4 or β1(M)=6. Finally we use TOP surgery to propose a characterization of the simplest embeddings of F×S1.