Several approaches have addressed unsupervised (Solan et al., 2005;van Zaanen and Adriaans, 2001) and semi-supervised (Wong and Meng, 2001;Siu and Meng, 1999;Meng and Siu, 2002) induction of grammars, where the latter may comprise manual post-processing of automatically induced rules.
in order to be applicable as an SLU model, semantic information must be added manually, since only syntactic structures can be induced automatically in this case.