In this paper, we write down a special Heegaard diagram for a given product threemanifold † g S 1 . We use the diagram to compute the perturbed c HF for the 3-torus and the perturbed HF C for nontorsion spin c -structures for † g S 1 when g 2.
53D401 IntroductionHeegaard Floer homology was introduced by Ozsváth and Szabó [4;5] and has proved to be a powerful 3-manifold invariant. The construction of the invariant requires an admissibility condition though, which in general is not met by those "simplest" Heegaard diagrams for a given 3-manifold Y with b 1 .Y / 1. A variant of the construction using the Novikov ring overcomes this shortcoming, and in some sense embraces the ordinary homology as a special case. The invariants, usually called perturbed Heegaard Floer homology, have proved to be useful in some situations. For example, Jabuka and Mark made use of them in calculating Ozsváth-Szabó invariants for certain closed 4-manifolds [1].This paper aims to compute the perturbed Heegaard Floer homologies for product three-manifolds † g S 1 . The result is a little surprising as we find that the homology groups are independent of the exact direction of perturbations.We would also like to point out that although the computation is made solely for the product three-manifolds in this paper, the method can in fact be applied to the more general setting of certain fibered three-manifolds; see the author's paper [8].This paper is organized as follows: In Section 2, we review the backgrounds of the Novikov ring A and the perturbed Heegaard Floer homology. Treating homology groups as A-vector spaces, we prove a rank inequality and an Euler characteristic identity. In Section 3, we write down a special Heegaard diagram for T 3 and compute its perturbed Heegaard Floer homology. In Section 4, we compute the homology for nontorsion Spin c structures for † g S 1 .