  We prove that the space of intertwining operators associated with certain
admissible modules over vertex operator algebras is isomorphic to a quotient of
the vector space of conformal blocks on a three-pointed rational curve defined
by the same data. This provides a new proof and alternative version of Frenkel
and Zhu's fusion rules theorem in terms of the dimension of certain bimodules
over Zhu's algebra, without the assumption of rationality.
