New applications such as CAD, AI, and hypermedia require direct representation and flexible use of complex objects, behavioral knowledge, and multimedia data. To this end, we have devised a knowledge base management system called Jasmine. An object-oriented approach in a programming language also seems promising for use in Jasmine. Jasmine extends the current object-oriented approach and provides the following features. Our object model is based on functional data models and well-established set theory. Attributes or functions composing objects can represent both structural and behavioral knowledge. The object model can represent incomplete and generic knowledge. The model can support the basic storage and operations of multimedia data. The facets of attributes can flexibly represent constraints and triggers. The object manipulation language can support associative access of objects. The structural and behavioral knowledge can be uniformly treated to allow the user to specify complex object operations in a compact manner. The user-defined and system-defined attributes can be uniformly specified to ease user customization of the language. The classes and instances can be uniformly accessed. Incomplete knowledge can be flexibly accessed. The system has a layered architecture. Objects are stored in nested relations provided by extensive DBMS as a sublayer. User query of objects is compiled into relational operations such as select and join, which can be efficiently processed using hashing. The behavioral knowledge is compiled into predicate and manipulation function interfaces that can directly access tuples in a buffer.— Authors' Abstract

No abstract

T his article presents a knowledge-based approach to designing portable natural language interfaces to database systems-an approach called KID (knowledge-based interface to database systems). To free users from needing to know about query languages and databases, and to provide users with access to databases in natural language, KID incorporates a knowledge base called the world model containing a domain model, linguistic knowledge, and database mapping knowledge. The world model is easy for users to define and understand; to transport KID to a new domain, the user has only to build a new world model for the domain. Using the world model, KID processes user queries transparently enough to enable easy user debugging of the world model. Since we have encapsulated domainspecific knowledge into the world model, KID is portable. This article will discuss world model design, and will examine KID's knowledge-based processing of queries using the world model. Numerous natural language interfaces to database systems have been developed in an attempt to make such systems more user friendly.1l2 Natural language interfaces must incorporate a knowledge base containing knowledge about a domain of discourse, databases, natural language, and a query language-thereby freeing users from needing to know about query languages and databases and enabling users to access databases in natural language. Moreover, applying natural language interfaces to new domains requires construction of new knowledge bases for those domains. Recent work focuses on portable natural language interface systems.3'4 However, no work has focused on the issues involved when users design knowledge bases by themselves to transport natural language interface systems to new domains-although one exception discusses some of these issues.5 -Gio Wiederhold Associate Editor

No abstract

No abstract