Tanaka and Iwasaki's (1996) optimization method for a translation-probability matrix mainly aims at adapting a bilingual dictionary to domains.
under the assumption that target word x and candidate translation equivalent y are characterized by first-language context vector a(x) = (a 1 (x), a 2 (x), …, a m (x)) and second-language context vector b(y) = (b 1 (y), b 2 (y), …, b n (y)), respectively, b(y) is translated into a first-language vector denoted as a'(y) = (a' 1 (y), where δ i,j =1 if the j-th element of b(y) is a translation of the i-th element of a(x); otherwise, δ i,j =0.