SMT has evolved from the original word-based approach (Brown et al., 1993) into phrase-based approaches (Koehn et al., 2003;Och and Ney, 2004) and syntax-based approaches (Wu, 1997;Alshawi et al., 2000;Yamada and Knignt, 2001;Chiang, 2005).
much important work continues to be carried out in Example-Based Machine Translation (EBMT) (Carl et al., 2005;Way and Gough, 2005), and many existing commercial systems are rule-based.