Many different learning approaches have been used, including neural networks (Leacock et al., 1993) , probabilistic algorithms (Bruce and Wiebe, 1994; Gale et al., 1992a; Gale et al., 1995; Leacock et al., 1993; Yarowsky, 1992) , decision lists (Yarowsky, 1994) , exemplar-based learning algorithms (Cardie, 1993; <cite>Ng and Lee, 1996)</cite> , etc.