�@I intoduce a cohomology-valued hypergeometric series 
which naturally arises in the description of (local) mirror symmetry. <BR>
�@I identify it as a central charge formula for BPS states and study its 
monodromy property from the viewpoint of homological mirror symmetry. 
In case of local mirror symmetry, I will make an explicit conjecture 
about an integral and symplectic monodromy property of the central 
charges. I will also present a closed formula of the prepotential at 
genus zero. <BR>
�@This talk is based on the preprint hep-th/0404043.