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A new generation of information systems that integrates knowledge base technology with database systems is presented for providing cooperative (approximate, conceptual, and asso-ciative) query answering. Based on the database schema and application characteristics, data are organized into Type Abstraction Hierarchies (TAHs). The higher levels of the(More)
We seek to give everyday technical teams the capability to build robust natural language interfaces to their databases, for subsequent use by casual users. We present an approach to the problem which integrates and streamlines earlier work based on light annotation and authoring tools. We model queries in a higher-order version of Codd's tuple calculus and(More)
This article presents C-Phrase, a natural language interface system that can be configured by normal, non-specialized, web-based technical teams. C-Phrase models queries in an extended version of Codd's tuple calculus and uses synchronous context free grammars with lambda-expressions to represent semantic grammars. Given an arbitrary rela-tional database,(More)
This article proposes a novel technique to generate natural language descriptions for a wide class of relational database queries. The approach to describing queries is phrasal and is restricted to a class of queries that return only whole schema tuples as answers. Query containment and equivalence are decid-able for this class and this property is(More)
In this paper we consider the processing of queries posed over multiple information resources that advertise their contents in terms of globally available, domain-specific on-tologies. We describe a technique to identify the exact portion of a user's query that may not be answered by the set of available information agents. This is achieved by reasoning(More)
This paper introduces schema tuple queries and argues for their suitability in representing knowledge over standard relational databases. Schema tuple queries are queries that return only whole tuples of schema relations. In particular a subclass of the schema tuple queries is identified that is decidable for satisfiability and is closed over syntactic(More)