In query-intensive database application areas, like decision support and data mining, systems that use vertical fragmentation have a significant performance advantage. In order to support relational or object oriented applications on top of such a fragmented data model, a flexible yet powerful

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, it can not test for a property that is simultaneously infinite and co-infinite (for example, parity). Then non-polynomial primitives such as powerbag, structural recursion and bounded loop are studied. Structural recursion on bags is shown to be strictly more powerful than the powerbag primitive

I am grateful to Luc Segoufin who kindly accepted me to be his PhD student. He introduced me to the problem of query enumeration and encouraged me to look for the answers to all the questions that emerged during our collaboration. He was a truly great advisor, always supportive and available

Algebraic methods in analyzing

fragment of it. A fragment is identified by using the explicit structure provided by the HTML tags as well as the implicit structure extracted using IR techniques. We define a query language, PIQL, that is a simple algebra extended with restructuring primitives. Our language expresses browsing

primitive, which can be used to assert the presence of a regular structure modelled within the XML. If this structure does exist, the data is extracted and presented as a typed value within the programming language. Overview Our context is standard programming languages used to query data formatted in XML

with freeze quantification. A freeze quantifier stores in a register the datum labelling the current tree node, which can then be accessed for equality comparisons deeper in the formula. The main results in the paper are that, for the fragment with forward modal operators and one register, satisfiability over

implementations of domain independent plans with with a structured notebook that the programmer uses to link object-oriented design primitives to arbitrary source code fragments. This jointly extracted information is used to support conceptual queries about the program's code and design. 1 Introduction

of the graphics pipeline. Using an SQLbased query language, the programmer can establish functional relationships among all the data, linking OpenGL state to primitives to vertices to fragments to pixels. Based on the Chromium library, our approach requires no modification to or recompilation of the program