The mapping q projects the multilingual words into the universal space based on their semantic similarity.
q(u|x) is a distribution based on the distance D s (u, x) between u and x as: where τ is a temperature and D(u i , x) is a scalar score which represents the similarity between source word x and universal token u i : where E K (u) is the "key" embedding of word u, E Q (x) is the "query" embedding of source word x.