Legendrian Realization in Convex Lefschetz Fibrations and Convex Stabilizations

TL;DR

This paper extends Giroux's Legendrian realization to convex open books in convex Lefschetz fibrations, establishing a correspondence between convex stabilizations and positive expansions, and demonstrating their effects on contact structures.

Contribution

It generalizes Legendrian realization to convex open books and links convex stabilizations with positive expansions of Lefschetz fibrations.

Findings

Any simply connected embedded Lagrangian in a convex open book can be Legendrianized.

Convex stabilizations correspond to convex stabilizations of Lefschetz fibrations.

Convex stabilization yields a positive expansion with contactomorphic boundaries.

Abstract

In this paper, we study compact convex Lefschetz fibrations on compact convex symplectic manifolds (i.e., Liouville domains) of dimension $2n+2$ which are introduced by Seidel and later also studied by McLean. By a result of Akbulut-Arikan, the open book on $\partial W$, which we call \emph{convex open book}, induced by a compact convex Lefschetz fibration on $W$ carries the contact structure induced by the convex symplectic structure (i.e., Liouville structure) on $W$. Here we show that, up to a Liouville homotopy and a deformation of compact convex Lefschetz fibrations on $W$, any simply connected embedded Lagrangian submanifold of a page in a convex open book on $\partial W$ can be assumed to be Legendrian in $\partial W$ with the induced contact structure. This can be thought as the extension of Giroux's Legendrian realization (which holds for contact open books) for the case of convex open books. Moreover, a result of Akbulut-Arikan implies that there is a one-to-one correspondence between convex stabilizations of a convex open book and convex stabilizations of the corresponding compact convex Lefschetz fibration. We also show that the convex stabilization of a compact convex Lefschetz fibration on $W$ yields a compact convex Lefschetz fibration on a Liouville domain $W'$ which is exact symplectomorphic to a \emph{positive expansion} of $W$. In particular, with the induced structures $\partial W$ and $\partial W'$ are contactomorphic.