Spontaneous speech parsing in travel information inquiring and booking systems

Grammar-based parsing is a prevalent method for natural language understanding (NLU) and has been introduced into dialogue systems for spoken language processing (SLP). A robust parsing scheme is proposed in this paper to overcome the notorious phenomena, such as garbage, ellipsis, word disordering, fragment, and ill-form, which frequently occur in spoken utterances. Keyword categories are used as terminal symbols, and the definition of grammar is extended by introducing three new rule types,by-passing, up-messing andovercrossing, in addition to the general rules calledup-tying in this paper, and the use of semantic items simplifies the semantics extraction. The corresponding parsermarionette, which is essentially a partial chart parser, is enhanced to parse the semantic grammar. The robust parsing scheme integrating the above methods has been adopted in an air traveling information service system calledEasyFlight, and has achieved a high performance when use for parsing spontaneous speeches.