Application of default reasoning to semantic processing under question-answering by

We build the natural language question-answering system, where the query representation formula is subject to transformation in accordance to the set of default rules. This transformation is required to disambiguate entities in a vertical domain, where they usually have a principle meaning and a set of foreign ones. Default reasoning is discussed to be applicable to a variety of semantic processing algorithms, including the semantic header approach. Using default rules can be referred as pragmatic machinery, complementary to syntactic and semantic processing of complex queries in a vertical domain. The methodology of building the set of default rules is developed, capable of adding the essential entities or eliminating misleading ones to the representation of input query. Implementation of operational semantics for default reasoning is suggested to transform the query representation by means of conflicting default rules. Technique of the keyword-based question answering is developed, where default rules link the set of potential queries with the initially coded canonical ones. The task of automatic annotation is then posed as building the set of keywords semantic headers and the set of canonical semantic headers for an answer.