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A classic problem in concurrent programming is that of the "dining philosophers" which challenges the power of any aspiring concurrent program language. Recently, a growing number of logic programming languages have been refined to handle concurrent programming, one in particular is Parlog86.With the increased sophistication demanded from software, in particular system cum environment software, it is increasingly complex and all too often bug-ridden. In theory, many approaches have been proposed for debugging and increasing confidence in the correctness of a program, some dealing with programming methodology and others with algebraic proof that a program does what the specification intends of it. In practice, for large programs, the most widely used methods are comprehensive test data and tracing of the computation. The art of bug detection with profilers, mutations, bounty hunters, and black teams has become a jargon generator in its own right. Increasingly, software developers begin with a specification of the functionality required by the software. Automatic verified code generation from a specification appears to be an emerging trend with sales of programmer workbenches gaining ground. An attractive alternative is a runnable specification combined with automatic, logically sound transformation from working specifications to efficient programs. There is a body of opinion (e.g., [9] and [20]), holding the belief that logic programs provide such runnable specifications.Insight into the relationship between specifications and programs can be drawn from some definitions proposed by Hoare [16] in relation to the concurrent programming language CSP. "A specification is a predicate describing all observations of a complex system." The predicate could be generalized into a set of logical formulas or sentences, but Hoare goes on to effectively include this possibility: "Specifications of complex sysFurlhfjr information conceriiing publications relating lo Parlog and details of the softwaro available can be obtained by writing lo .

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The regularization of the Kepler problem proposed by Kustaanheimo and Stiefel provides an example of quantum mechanics on the quotient of a conformally flat manifold.

Internet programming languages such as Java present new challenges to garbage-collection design. The spectrum of garbage-collection schema for linked structures distributed over a network are reviewed here. Distributed garbage collectors are classified first because they evolved from single-address-space collectors. This taxonomy is used as a framework to explore distribution issues: locality of action, communication overhead and indeterministic communication latency.