Some of the previous methods tried to alleviate the problem of the limited seed lexicon size (Koehn and Knight, 2002;Morin and Prochasson, 2011;Hazem et al., 2011), while others did not require any seed lexicon (Rapp, 1995;Fung, 1995;Haghighi et al., 2008;Ismail and Manandhar, 2010;Daumé III and Jagarlamudi, 2011).
the first of these types are words whose equivalent does not exist in the English corpus.