mHG definition:

   mHG(lambdas) = min over 1 <= n <= N Of HGT (b_n(lambdas); N, B, n)

Where HGT Is the hypergeometric tail:

   HGT(b; N, B, n) = Probability(X >= b)

And:

   b_n = sum over 1 <= i <= n Of lambdas[i]