Let s i and s j be two tokenised and truecased sentences in languages l 1 and l 2 , respectively, S i the set of tokens in s i , S j the set of tokens in s j , T ij the set of expanded translations into l 2 for all tokens in S i , and T ji the set of expanded translations into l 1 for all tokens in S j .
the StACC similarity score is then computed as in Equation 1: (1) the score is defined as the average of the Jaccard similarity coefficients obtained between sentence token sets and expanded lexical translations in both directions.