From Theorem 2, for target language, with probability at least 1 − δ, For the source language, similarly, with probability at least 1 − δ, Given a word type w T , we notice that only the KL-divergence term in ϵ(x T , w S ) varies among different tokens x T .
we use KL w S and KL w T to denote the maximal values of KLdivergence over all the tokens, Let n = min {n w T , n w S }, and n ⋆ = max {n w T , n w S }.