  We construct the fusion product of finite-dimensional sl_2-modules in the
homology of (or in the space of constructible functions on) a certain
subvariety L_l(w_1, ..., w_r) of Nakajima's tensor product variety L(w_1,...,
w_r). We also give a combinatorial description of the irreducible components of
this subvariety using the notions of graphical calculus and crossingless
matches for sl_2.
