For the special case of Schur functions, we have the Jacobi-Trudi identity which can expresses $s_{\lambda/\mu}$ as a determinant. I wonder if there is any similar formulas for the general case $P_{\lambda/\mu}$? If such a formula does not exit, can anyone show me some references which could be helpful to compute the specialization(let $x_i=t^{i-1}$) of $P_{\lambda/\mu}$, at least for small $\lambda$ and $\mu$? Thanks.