Bijan Sahamie

  1. Holomorphic discs and surgery exact triangles.

    Authors: Bijan Sahamie
    Subjects: Geometric Topology
    Abstract

    We show a connection between the surgery exact sequence in knot Floer
    homology and the sequence derived in [15]. As a result we may interpret the
    maps \Gamma_1 and \Gamma_2 from [15] as counting small holomorphic triangles in
    a suitable Heegaard triple diagram. Consequently, the exact sequence in [15]
    also works with coherent orientations and admits refinements with respect to
    Spinc structures. The vanishing results of the contact element from [15] thus
    generalize to \Z-coefficients.

  2. Dehn Twists in Heegaard Floer Homology.

    Authors: Bijan Sahamie
    Subjects: Geometric Topology
    Abstract

    We derive a new exact sequence in the hat-version of Heegaard Floer homology.
    As a consequence we see a functorial connection between the invariant of
    Legendrian knots and the contact element. As an application we derive two
    vanishing results of the contact element making it possible to easily read off
    its vanishing out of a surgery representation in suitable situations.

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