S-stable foliations on flow-spines with transverse Reeb flow

Abstract

The notion of S-stability of foliations on branched simple polyhedrons is introduced by R. Benedetti and C. Petronio in the study of characteristic foliations of contact structures on 3-manifolds. We additionally assume that the 1-form $\beta$ defining a foliation on a branched simple polyhedron $P$ satisfies $d\beta>0$, which means that the foliation is a characteristic foliation of a contact form whose Reeb flow is transverse to $P$. In this paper, we show that if there exists a 1-form $\beta$ on $P$ with $d\beta>0$ then we can find a 1-form with the same property and additionally being S-stable. We then prove that the number of simple tangency points of an S-stable foliation on a positive or negative flow-spine is at least 2 and give a recipe for constructing a characteristic foliation of a 1-form $\beta$ with $d\beta>0$ on the abalone.