Philip M. Lewis

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Several polynomial time algorithms finding “good,” but not necessarily optimal, tours for the traveling salesman problem are considered. We measure the closeness of a tour by the ratio of the obtained tour length to the minimal tour length. For the nearest neighbor method, we show the ratio is bounded above by a logarithmic function of the number of nodes.(More)
A transduction is a mapping from one set of sequences to another. A syntax-directed transduction is a particular type of transduction which is defined on the grammar of a context-free language and which is meant to be a model of part of the translation process used in many compilers. The transduction is considered from an automata theory viewpoint as(More)
A distributed database system is one in which the database is spread among several sites and application programs “move” from site to site to access and update the data they need. The concurrency control is that portion of the system that responds to the read and write requests of the application programs. Its job is to maintain the global(More)
The Concurrency Factory supports the speciication, simulation , veriication, and implementation of real-time concurrent systems such as communication protocols and process control systems. While the system uses process algebra as its underlying design formalism, the primary focus of the project is practical utility: the tools should be usable by engineers(More)
UNLABELLED It is common for depression to develop after traumatic brain injury (TBI), yet despite poorer recovery, there is a lack in our understanding of whether post-TBI brain changes involved in depression are akin to those in people with depression without TBI. Modern neuroimaging has helped recognize degrees of diffuse axonal injury (DAI) as being(More)
This book Databases and Transaction Processin 9 constitutes a standard database textbook for advanced undergraduate and graduate courses-albeit with a somewhat different focus compared to the established books. As the subtitle A n A pplicationOriented ,4 pproach indicates, the authors put an emphasis on teaching the systematic usage of database sys tems~ra(More)