Stephen Johnson

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Emerging multimedia applications require database systems to provide support for new types of objects and to process queries that may have no parallel in traditional database applications. One such important class of queries are the proximity queries that aims to retrieve objects in the database that are related by a distance metric in a way that is(More)
This paper presents a research carried out at the BT IT Mobility Research Centre starting in August 2004 with the aim of uncovering the user experience in future scenarios of mobile and pervasive iTV, paying special attention to the new contextual usage of this media within the entertainment, work and government environments. It uses innovative(More)
ht this work we describe a new app-oach using relative debugging to find differences in compmation between a serial program and a parallel version of tl at program. We use a combination of re-execution and backtracking in order to find the first difference in computation that may ultimately lead to an incorrect value that the um r has indicated. In our(More)
This paper formalizes term rewriting systems (TRSs), called <i>scoped</i>, in which a rewrite rule can be nested within another rewrite rule. The right-hand side and/or the condition of a nested rule can refer to any variable in the left-hand side of a nesting rule. Nesting of rewrite rules is intended to define a lexical scope with static binding. Our work(More)