For single databases, primary hindrances for end-user access are the volume of data that is becoming available, the lack of abstraction, and the need to understand the representation of the data. When information is combined from multiple databases, the major concern is the mismatch encountered in information representation and structure. Intelligent and active use of information requires a class of software modules that mediate between the workstation applications and the databases. It is shown that mediation simplifies, abstracts, reduces, merges, and explains data. A mediator is a software module that exploits encoded knowledge about certain sets or subsets of data to create information for a higher layer of applications. A model of information processing and information system components is described. The mediator architecture, including mediator interfaces, sharing of mediator modules, distribution of mediators, and triggers for knowledge maintenance, are discussed. >

Mediators in the architecture of future information systems

During the past two years, the Dempster-Shafer theory of evidence has attracted considerable attention within the AI community as a promising method of dealing with uncertainty in expert systems. As presented in the literature, the theory is hard to master. In a simple approach that is outlined in this paper, the Dempster-Shafer theory is viewed in the context of relational databases as the application of familiar retrieval techniques to second-order relations in first normal form. The relational viewpoint clarifies some of the controversial issues in the Dempster-Shafer theory and facilities its use in AI-oriented applications.

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A simple view of the Dempster-Shafer theory of evidence and its implication for the rule of combination

This paper is an introduction to natural language interfaces to databases (NLIDBs). A brief overview of the history of NLIDBs is first given. Some advantages and disadvantages of NLIDBs are then discussed, comparing NLIDBs to formal query languages, form-based interfaces, and graphical interfaces. An introduction to some of the linguistic problems NLIDBs have to confront follows, for the benefit of readers less familiar with computational linguistics. The discussion then moves on to NLIDB architectures, portability issues, restricted natural language input systems (including menu-based NLIDBs), and NLIDBs with reasoning capabilities. Some less explored areas of NLIDB research are then presented, namely database updates, meta-knowledge questions, temporal questions, and multi-modal NLIDBs. The paper ends with reflections on the current state of the art.

Natural Language Interfaces to Databases - An Introduction

This paper is an introduction to natural language interfaces to databases (NLIDBS). A brief overview of the history of NLIDBS is first given. Some advantages and disadvantages of NLIDBS are then discussed, comparing NLIDBS to formal query languages, form-based interfaces, and graphical interfaces. An introduction to some of the linguistic problems NLIDBS have to confront follows, for the benefit of readers less familiar with computational linguistics. The discussion then moves on to NLIDB architectures, portability issues, restricted natural language input systems (including menu-based NLIDBS), and NLIDBS with reasoning capabilities. Some less explored areas of NLIDB research are then presented, namely database updates, meta-knowledge questions, temporal questions, and multi-modal NLIDBS. The paper ends with reflections on the current state of the art.

Natural language interfaces to databases-An introduction

User models have recently attracted much research interest in the field of artificial intelligence dialog systems. It has become evident that a flexible user-oriented dialog behavior of such systems can be realized only if the system disposes of a model of the user, containing assumptions about the user`s background knowledge as well as the user`s goals and plans in consulting the system. Research in the field of user models investigates how such assumptions can be automatically created, represented and exploited by the system in the course of an interaction with the user. This volume is the first survey pertaining to the field of user modeling. Most of the prominent international researchers in this area have contributed to this volume. Their papers are grouped into four sections: The introductory section contains a general view of the field as a whole, and a number of surveys of specific problems and techniques in user modeling. Sections two and three describe eight user modeling systems, with the focus lying on the automatic creation and exploitation of assumptions about the user respectively. The final section discusses several limits of current systems, and proposes solutions as to how some of the shortcomings might be overcome. In order to increase the quality and the coherency of the volume, each paper has been reviewed by all other contributors. Cross-references have been integrated wherever appropriate. All contributions are introduced in editorial prefaces pertaining to each section. A subject index and an extensive bibliography supplement the book.

http://www.dfki.de/wwdata/Publications/User_Models_in_Dialog_Systems.pdf

User Models in Dialog Systems

Cooperative responses from a portable natural language query system

One barrier to the acceptance of natural language database query systems is the substantial installation effort required for each new database. Much of this effort involves the encoding of semantic knowledge for the domain of discourse, necessary to correctly interpret and respond to natural language questions. For such systems to be practical, techniques must be developed to increase their portability to new domains.This paper discusses several issues involving the portability of natural language interfaces to database systems, and presents the approach taken in CO-OP — a natural language database query system that provides cooperative responses to English questions and operates with a typical CODA-SYL database system. CO-OP derives its domain-specific knowledge from a lexicon (the list of words known to the system) and the information already present in the structure and content of the underlying database. Experience with the implementation suggests that strategies that are not directly derivative of cognitive or linguistic models may nonetheless play an important role in the development of practical natural language systems.

Designing a Portable Natural Language Database Query System

Since cooperation is an essential aspect of human conversation, it is a necessary feature in a natural language interface. Previous work has shown that it is possible to incorporate principles of cooperative behaviour into a system allowing natural language access to a database. It is shown here that some of these principles can also be applied fruitfully in a formal language environment. Specifically, when a query retrieves an empty result set, it is possible, by analyzing the question and running related queries against the database, to give a useful explanation of the zero result. A precise specification of the information that should be presented to the user is described for queries consisting of boolean combinations of predicates of a single variable. Such cooperative responses to boolean queries have been implemented on the large bibliographic database of the Research Libraries Group. The size of the database has motivated a careful optimization of the algorithm, which is discussed.

Cooperative responses to boolean queries

Although the problems of querying databases in natural language are well understood, the performance of database updates via natural language introduces additional difficulties. This thesis examines the problems encountered in interpreting natural language updates, and describes an implemented system that performs simple updates.
The difficulties associated with natural language updates results from the fact that the user will naturally phrase requests with respect to his conception of the domain, which may be a considerable simplification of the actual underlying database structure. Updates that are meaningful and unambiguous from the user's standpoint may not translate into reasonable changes to the underlying database.
The PIQUE system (Program for Interpretation of Queries and Updates in English) operates by maintaining a simple model of the user and interpreting update requests with respect to that model. For a given request, a limited set of "candidate updates"--alternative ways of fulfilling the request--are considered, and ranked according to a set of domain-independent heuristics that reflect general properties of "reasonable" updates. The leading candidate may be performed, or the highest ranking alternatives presented to the user for selection. The resultant action may also include a warning to the user about unanticipated side effects, or an explanation for the failure to fulfill a request.
This thesis describes the PIQUE system in detail, presents examples of its operation, and discusses the effectiveness of the system with respect to coverage, accuracy, efficiency, and portability. The range of behaviors required for natural language update systems in general is discussed, and implications of updates on the design of data models are briefly considered.

Interpreting natural language database updates

: For natural language database systems to operate effectively in practical domains, they must have the capabilities required by real applications. One such capability is understanding and performing update requests. The processing of natural language updates raises problems not encountered in the processing of queries. These difficulties stem from the fact that the user will naturally phrase requests with respect to his conception of the domain, which may be a considerable simplification of the actual underlying database structure. Updates which are meaningful and unambiguous from the user's standpoint may not translate into reasonable changes to the underlying database. Update requests may be impossible (cannot be performed in any way), ambiguous (can be performed in several ways), or pathological (can be performed only in ways which cause undesirable side effects). Drawing on work in Linguistics and Philosophy of Language, we have developed a domain-transparent approach to identifying and performing 'reasonable' changes in response to a user's update request, using only knowledge sources typically present in existing database systems. A simple notion of 'user model' and explanation with respect to the user's state of knowledge are central to the design. This paper describes a system PIQUE (Program for Interpreatation of Query/Update in English), which implements this approach. (Author)

S. Jerrold Kaplan

Papers

Cooperative responses from a portable natural language query system

Designing a Portable Natural Language Database Query System

Cooperative responses to boolean queries

Interpreting natural language database updates

Natural Language Access to Databases: Interpreting Update Requests