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PUBLICATIONS

1993

Many current relational database systems use some form of histograms to approximate the frequency distribution of values in the attributes of relations and based on them estimate query result sizes…
Fox (Finding Objects of eXperiments) is the declarative query language for Moose (Modeling Objects Of Scientific Experiments), an object-oriented data model at the core of a scientific experiment…
In this paper, we carefully explore the assumptions behind using information capacity equivalence as a measure of correctness for judging transformed schemas in schema integration and translation…
Before the problem of schema integration and translation can be adequately addressed, a precise understanding of schemas is needed. We present an analysis of the notion of schema as used by…
Traditionally, the scale and scope of an experimental study was determined by the ability of the research team to generate data. Over the past few years, we have been experiencing an unprecedented…

1992

When a set of rules generates (conflicting) values for a virtual attribute of some tuple, the system must resolve the inconsistency and decide on a unique value that is assigned to that attribute.…
In this paper, we identify some of the fundamental issues that must be addressed in designing a desktop Experiment Management System (EMS). We develop an abstraction of the set of activities…
We investigate the role of commutativity in query processing of linear recursion. We give a sufficient condition for two linear, function-free, and constant-free rules to commute. The condition…
This paper presents the results of an experimental evaluation of the performance of three main algorithms for transitive closure: Seminaive, Smart and Blocked Warren. The algorithms have been…
In most database systems, the values of many important run-time parameters of the system, the data, or the query are unknown at query optimization time. Parametric query optimization attempts to…
This paper examines the idea of incorporating machine Iearning algorithms into a database system for monitoring its stream of incoming queries and generating hierarchies with the most important…
If one were to conduct a survey among researchers from all sciences asking for the greatest challenges in their particular discipline, one would expect very different answers from scientists of…
We describe an effort to develop a prototype database system for scientific data generated from controlled experiments or direct observations and concentrate on the user interface module of the…

1991

Current query optimization techniques are inadequate to support some of the emerging database applications. In this paper, we outline a database query optimization problem and describe the…
We present a combination of analytical and experimental results that shed some light into the shape of the cost function of the strategy spaces that query optimizers must deal with. These are the…
Query optimizers of current relational database systems use several statistics maintained by the system on the contents of the database to decide on the most efficient access plan for a given query…
An algebraic framework for the study of recursion has been developed. For immediate linear recursion, a Horn clause is represented by a relational algebra operator. It is shown that the set of all…

1990

Query optimization for relational database systems is a combinatorial optimization problem, which makes exhaustive search unacceptable as the query size grows. Randomized algorithms, such as…

1989

We investigate the role of commutativity in query processing of linear recursion. We give a sufficient condition for two linear, function-free, and constant-free rules to commute. The condition…
In the majority of research work done on logic programming and deductive databases, it is assumed that the set of rules defined by the user is consistent, i.e., that no contradictory facts can be…

1988

We have developed some efficient algorithms for computing the transitive closure of a directed graph. This paper presents the algorithms for the problem of reachability. The algorithms, however,…
As the size and complexity of processing and manufacturing systems increases, the need for Database Management Systems (DBMS) that meet the special needs of studies that experiment with such…
We describe the design and implementation of BERMUDA, which is a system interfacing Prolog to the Britton-Lee Intelligent Database Machine (IDM). We discuss several architectural issues faced by such…
Consider a function-free and constant free Horn clause [Gall 78]... (cannot display further due to mathematical functions that cannot be expressed in text - please donwload paper instead).

1987

Query optimizers of future database management systems are likely to face large access plan spaces in their task. Exhaustively searching such access plan spaces is unacceptable. We propose a query…

1986

A virtual relation (or view) can be defined with a recursive Horn clause that is a function of one or more base relations. In general, the number of times such a Horn clause must be applied in order…
Query processing in the presence of recursively defined views usually involves some form of iteration. For example, computing the transitive closure of a tree involves iterating N times, where N is…
Recursion in the database context has traditionally been studied under the formalism of 1-st order logic. In particular, the bulk of the research effort in the last few years has been devoted to…

1985

A virtual relation (or view) can be defined with a recursive statement that is a function of one or more base relations. In general, the number of times such a statement must be applied in order to…

1984

This paper proposes extensions to a relational database system to support the selection and execution of algorithms for shortest path search problems. An expert system can employ this extended DBMS…