\[P(\mathbf{x})=\sum_{\boldsymbol{{\alpha}}}c_{\boldsymbol{{\alpha}}}\mathbf{x}^%
{\boldsymbol{{\alpha}}}=\sum_{\boldsymbol{{\alpha}}}c_{\boldsymbol{{\alpha}}}x%
_{1}^{\alpha_{1}}\cdots x_{n}^{\alpha_{n}},\]