This is LaTeX code:

[latex]
M\left( {e^{j_1 } ,...,e^{j_k } } \right) = \sum\limits_{\left[ I \right]} {M\left( {e^{i_1 } ,...,e^{i_k } } \right)dx_I \left( {e^{j_1 } ,...,e^{j_k } } \right)} =
[/latex]