Comultiplicativity of the Ozsvath-Szabo contact invariant
Abstract
Suppose that S is a surface with boundary and that g and h are diffeomorphisms of S which restrict to the identity on the boundary. Let Y_g, Y_h, and Y_{hg} be the three-manifolds with open book decompositions given by (S,g), (S,h), and (S,hg), respectively. We show that the Ozsvath-Szabo contact invariant is natural under a comultiplication map on Heegaard Floer homology. It follows that if the contact invariants associated to the open books (S, g) and (S, h) are non-zero then the contact invariant associated to the open book (S, hg) is also non-zero. We extend this comultiplication to a map on HF^+, and as a result we obtain obstructions to the three-manifold Y_{hg} being an L-space. We also use this to find restrictions on contact structures which are compatible with planar open books.
Keywords
Cite
@article{arxiv.math/0702603,
title = {Comultiplicativity of the Ozsvath-Szabo contact invariant},
author = {John A. Baldwin},
journal= {arXiv preprint arXiv:math/0702603},
year = {2007}
}
Comments
15 pages, 4 figures. This updated version contains a generalization of the main theorem from before, with consequences relating to the planarity of open books, and Heegaard Floer L-spaces