Data Flow Program Graphs

Data flow languages form a subclass of the languages which are based primarily upon function application (i.e., applicative languages). By data flow language we mean any applicative language based entirely upon the notion of data flowing from one function entity to another or any language that directly supports such flowing. This flow concept gives data flow languages the advantage of allowing program definitions to be represented exclusively by graphs. Graphical representations and their applications are the subject of this article

Dynamic Systolization for Developing Multiprocessor Supercomputers

A dynamic network approach is introduced for developing reconfigurable, systolic arrays or wavefront processors; This allows one to design very powerful and flexible processors to be used in a general-purpose, reconfigurable, and fault-tolerant, multiprocessor computer system. The concepts of macro-dataflow and multitasking can be integrated to handle variable-resolution granularities in computationally intensive algorithms. A multiprocessor architecture, Remps, is proposed based on these design methodologies. The Remps architecture is generalized from the Cedar, HEP, Cray X- MP, Trac, NYU ultracomputer, S-l, Pumps, Chip, and SAM projects. Our goal is to provide a multiprocessor research model for developing design methodologies, multiprocessing and multitasking supports, dynamic systolic/wavefront array processors, interconnection networks, reconfiguration techniques, and performance analysis tools. These system design and operational techniques should be useful to those who are developing or evaluating multiprocessor supercomputers

The application of message passing to concurrent programming

The development of concurrency in computer systems will be critically reviewed and an alternative strategy proposed. This is a programming language designed along semantic principles, and it is based upon the treatment of concurrent processes as values within that language's universe of discourse. An asynchronous polymorphic message system is provided to enable co-existent processes to communicate freely. This is presented as a fundamental language construct, and it is completely general purpose, as all values, however complex, can be passed as messages. Various operations are also built into the language so as to permit processes to discover and examine one another. These permit the development of robust systems, where localised failures can be detected, and action can be taken to recover. The orthogonality of the design is discussed and its implementation in terms of an incremental compiler and abstract machine interpreter is outlined in some detail. This thesis hopes to demonstrate that message-oriented communication in a highly parallel system of processes is not only a natural form of expression, but is eminently practical, so long as the entities performing the communication are values in the languag

Interprocess communication in highly distributed systems

Issued as Final technical report, Project no. G-36-632Final technical report has title: Interprocess communication in highly distributed system

A powerdoman semantics for indeterminism

A denotational semantics is presented for a language that includes multiple-valued functions (essentially Lisp S-expressions), which map from ground values into the power domain of ground values. The domain equations are reflexive. and fixed points of all functions are defined. Thus, it is possible to specify an operating system as a function whose codomain is a set of possible behaviors of the system, only one of which is realized under an operational semantics. Such a system can be specified using "pure" applicative programming (recursion equations without side effects) over primitive functions like amb, frons, arbiter, or arbit, all of which are formally defined. Tempered by 'environmental transparency,' we consider a power domain semantics in which the power domain may only occur within the codomain in the equation that defines func­tion space. The problem addressed is how to define the analog of 'fixed point' for a function from the ground domain to that power domain, in a semantics that uses natural extension as the axiom for function application. Denotational and equivalent operational semantics are presented for the Smyth-upside-down power domain; a similar denotational semantics is presented for the Plotkin power domain (Egli-Milner order), along with a likely operational semantics

Processes and interactions : an approach to the modelling of industrial systems

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Concurrent Operations in Persistent Search Trees

Computing and Information Scienc