Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"relational algebra"”.
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Formal Verification of Relational Algebra Transformations in Fiat2 Using Coq
… as filtering, joining, and projecting records. Relational database systems generally use query planners to optimize high-level SQL queries into efficient execution plans. While these systems apply well-established query transformations, they typically assume the correctness of these …
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nD-SQL : extending schemaSQL towards multidimensional databases and OLAP
… proposes a formal model for a federation of relational databases with possibly heterogeneous schemas. The Federation Model is comprehensive enough for: (i) capturing the diversity of schemas arising in practice, allowing a symmetric treatment of data and schema, and (ii) capturing the …
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Database implementation on an object-oriented processor architecture
… level consisting of an implementation of the relational algebra.<br/>• an internal level provided by the REKURSIV system.<br/><br/>The mapping of the external to the conceptual levels is achieved through a recursive descent interpreter which was machine generated from a syntax …
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Attribution principles for data integration : technology and policy perspectives
… are defined, implementation in an extended relational algebra is described, and application to semistructured data on the Web is discussed. However, because the problem is more than simply what and where, we then expand the scope of our analysis. From the perspective of intellectual property …
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A database query language for operations on historical data
… time processing capabilities into the relational model. The role of time in this model is examined, as is the effect of time on relational algebra. An algebra for historical relations is defined.<br/><br/>Finally the Historical Query Language (HQL) is defined and implemented. HQL is …
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Declarative Analytics on Heterogeneous HPC Systems
… queries, which can be efficiently compiled into relational algebra operations for execution on GPGPUs. Integrating Datalog's declarative syntax with GPGPU's computational power enables scalable declarative analytics across big data, graph mining, and program analysis on HPC systems. While recent …
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APPROXIMATE: A Query Processor That Produces Monotonically Improving Approximate Answers
… algorithm of APPROXIMATE works within a standard relational algebra framework.
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Validation of queries to a relational database
… intentions. A method of assisting users of a relational data base to formulate query language expressions which are valid representations of the abstract query which the user wishes to put is developed. The central focus of the thesis is a method of communicating the critical aspects of the …
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Towards an implementation of SchemaLog : a database programming language
… SchemaLog constructs into an extended version of relational algebra called Schema Algebra (${\cal {SA}}$). We modify the new operators in this algebra to suit our implementation, and we illustrate how a SchemaLog program can be evaluated by conversion into an expression in ${\cal {SA}}$. Based on …
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A database query language for operations on graphical objects
… this work arose from the recognised inability of relational databases to store and manipulate data that is outside normal commercial applications (e.g. graphical data).<br/><br/>The published work in this area is described with respect to the major problems of representation and manipulation of …
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Aggregation in temporal databases
Temporal database systems extend relational database systems to support time-varying information. One important such extension is support for time-varying aggregate functions, such as a time-varying average. Our research will show that temporal aggregates may be specified in a semantically well …
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Towards DIVE : A platform for automatic visualization and analysis of structured datasets
… conceptual framework inspired by set theory and relational algebra, and drawing upon existing work in visualization and database architecture. With these analytical abstractions, we rigorously characterize datasets, infer data models, enumerate visualizable or analyzable data structures, and …
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Dynamic Integration of Evolving Distributed Databases using Services
… by database evolution. An algorithm, named Relational Schema Mapping by Views (RSMV), is designed to integrate source databases that are exposed as services into a pre-designed global schema that is in a data integrator service. Instead of producing hard-coded programs, views are built using …
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P-Pascal : a data-oriented persistent programming language
… data collections in a persistent environment. Relational algebra operators are provided and the automatic optimisation of set expressions is performed by the compiler and the runtime system. The P-Pascal Abstract Machine incorporates two complementary data placement strategies, automatic …
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Query processing in heterogeneous distributed database management systems
… addressed the first issue by developing an algebraic query language called cluster algebra. The cluster algebra consists of the following operations: (a) Selection, union, intersection and difference, which are extensions of their relational algebraic counterparts to heterogeneous databases; …
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A foundation for integrating heterogeneous data sources
… besides well-structured data sources (such as relational databases), semi-structured data sources (such as the HTML documents on the World Wide Web). Our approach is declarative and is based on a simple logic called SchemaLog. SchemaLog's syntax is higher-order but it enjoys a first-order …
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Data mining using L-fuzzy concept analysis.
… their attributes by yes-no entries. We propose a relational theory for generating attribute implications from many-valued contexts, i.e, where the relationship between objects and attributes is given by a range of degrees from no to yes. This degree is usually taken from a suitable lattice where …