On the effective dimension and multilevel Monte Carlo
I consider the problem of integrating a function f over the d-dimensional unit cube. I describe a multilevel Monte Carlo method that estimates the integral with variance at most ϵ^2 in O(d+ln(d)d_tϵ^-2) time, for ϵ>0, where d_t is the truncation dimension of f. In contrast, the standard Monte Carlo method typically achieves such variance in O(dϵ^-2) time. A lower bound of order d+d_tϵ^-2 is described for a class of multilevel Monte Carlo methods.
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