Variance reduced multilevel path simulation: going beyond the complexity   $\varepsilon^{-2}$
  In this paper a novel modification of the multilevel Monte Carlo approach, allowing for further significant complexity reduction, is proposed. The idea of the modification is to use the method of control variates to reduce variance at level zero. We show that, under a proper choice of control variates, one can reduce the complexity order of the modified MLMC algorithm down to $\varepsilon^{-2+\delta}$ for any $\delta\in [0,1)$ with $\varepsilon$ being the precision to be achieved. These theoretical results are illustrated by several numerical examples. 
Denis Belomestny and Tigran Nagapetyan
q-fin.CP math.PR