Non-isotopic transverse tori in Engel manifolds

Abstract

In every Engel manifold, we construct an infinite family of pairwise nonisotopic transverse tori that are all smoothly isotopic. To distinguish the transverse tori in the family, we introduce a homological invariant of transverse tori that is similar to the self-linking number for transverse knots in contact 3-manifolds. Analogous results are presented for Legendrian tori in even contact 4-manifolds.