“…The twisted de Rham theory developed by Aomoto [1], [3], [6] has brought a unified treatment, and a systematic way of generalization, of various hypergeometric integrals which were invented and investigated by many authors. According to Aomoto, any such integral is interpreted as a pairing of a homology class and a cohomology class on a complex projective space P n minus an effective divisor D with coefficients in a local system of rank one, which is defined by a multi-valued function on P n ramified just along D. Moreover, knowing the structures of the corresponding homology and cohomology groups enables us not only to produce systematically a system of differential equations satisfied by such integrals but also to determine the connection formulae and the monodromy representations of such integrals [2], [4], [5].…”