  In a previous paper we constructed all polynomial tau-functions of the
1-component KP hierarchy, namely, we showed that any such tau-function is
obtained from a Schur polynomial $s_\lambda(t)$ by certain shifts of arguments.
In the present paper we give a simpler proof of this result, using the
(1-component) boson-fermion correspondence. Moreover, we show that this
approach can be applied to the s-component KP hierarchy, using the s-component
boson-fermion correspondence, finding thereby all its polynomial tau-functions.
We also find all polynomial tau-functions for the reduction of the s-component
KP hierarchy, associated to any partition consisting of s positive parts.
