https://s0.wp.com/latex.php?latex=%5Cdisplaystyle++%5Clim_%7BN%5Crightarrow%5Cinfty%7D%5Cfrac1N%5Csum_%7Bn%3D1%7D%5EN%5Cint_Xf_0%5Ccdot%5Cprod_%7Bp%5Cin%7B%5Cmathcal+P%7D%7DT%5E%7Bp%28n%29%7Df_pd%5Cmu%3D0%5Cqquad+%5Ctext%7B+for+any+%7Df_p%5Cin+L%5E%5Cinfty%28X%29+%5C+%5C+%5C+%5C+%5C+%281%29&bg=ffffff&fg=000000&s=0