An operational framework for value-passing processes

Lecture Notes in Computer Science, 2017

We present a Unifying Theories of Programming (UTP) semantics of shared variable concurrency that is fully compositional. Previous work was based on mapping such programs, using labelling of decision points and atomic actions, to action systems, which themselves were provided with a UTP semantics. The translation to action systems was largely compositional, but their dynamic semantics was based on having all the actions collected together. Here we take a more direct approach, albeit inspired by the action-systems view, based on an abstract notion of label generation, that then exploits the standard use of substitution in UTP, to obtain a fully compositional semantics.

Electronic Notes in Theoretical Computer Science, 1999

Electronic Proceedings in Theoretical Computer Science, 2012

We propose a novel, operational framework to formally describe the semantics of concurrent programs running within the context of a relaxed memory model. Our framework features a "temporary store" where the memory operations issued by the threads are recorded, in program order. A memory model then specifies the conditions under which a pending operation from this sequence is allowed to be globally performed, possibly out of order. The memory model also involves a "write grain," accounting for architectures where a thread may read a write that is not yet globally visible. Our formal model is supported by a software simulator, allowing us to run litmus tests in our semantics.

1996

This paper presents an imperative and concurrent extension of the functional object-oriented calculus described in . It belongs to the family of so-called prototype-based object-oriented languages, in which objects are created from existing ones via the inheritance primitives of object extension and method override. Concurrency is introduced through the identification of objects and processes. To our knowledge, the resulting calculus is the first concurrent object calculus to be studied. We define an operational semantics for the calculus via a transition relation between configurations, which represent snapshots of the run-time system. Our static analysis includes a type inference system, which statically detects message.not.understood errors, and an effect system, which guarantees that synchronization code, specified via guards, is side-effect free. We present a subject reduction theorem, modified to account for imperative and concurrent features, and type and effect soundness theorems.

Corr, 2007

Message passing is a key ingredient of concurrent programming. The purpose of this paper is to describe the equivalence between the proof theory, the categorical semantics, and term calculus of message passing. In order to achieve this we introduce the categorical notion of a linear actegory and the related polycategorical notion of a poly-actegory. Not surprisingly the notation used for the term calculus borrows heavily from the (synchronous) pi-calculus. The cut elimination procedure for the system provides an operational semantics.

In this paper we present an operational semantics for concurrent interactive process es in the purely functional programming language Clean. An interactive process is in essence a state transition system which apart from its logical state can also access the state of the file system, do highlevel Graphical User I/O, and do inter-process communication via synchronous and asynchronous message passing and data sharing. Inter-process communication is type-safe and polymorphic. The semantics of the system is based on earlier work on the Interleaved Event I/O system. In this paper we identify limitations of the interleaved model in the context of concurrent processes and propose a new process semantics that does allow a concurrent implementation. The method basically intro duces a Remote Procedure Call communication scheme and demonstrates how to apply this scheme to obtain a concurrent process semantics. The resulting system is the Concur rent Event I/O system . The operational semantics is given in Clean itself. As a result the concurrency system is completely func tional because the construction is done within the pure functional framework.

Theoretical Computer Science, 1999

This paper studies causality in the x-calculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. Our studies show that two transitions not causally related may however occur in a fixed ordering in any computation, i.e., the z-calculus may implicitly express a precedence between actions. The same partial order of transitions is associated with all the computations that are obtained by shuffling transitions that are concurrent (i.e. related neither by causality nor by precedence). Other non-interleaving semantics are investigated and compared. The presentation takes advantage of a parametric definition of process behaviour given in SOS style that permits us to take almost for free the interleaving theory and tools. Finally, we extend our approach to higherorder n-calculus, enriched with a spurn operation. @ 1999-Elsevier Science B.V. All rights rcscrvcd . 0304-3975/99/$ -see front matter @ 1999-Elsevier Science B.V. All rights reserved I'll: SO304-3975(97)00236-3

Lecture Notes in Computer Science, 1997

We present a new type system for TyCO, a name-passing calculus of concurrent objects. The system captures dynamic aspects of the behaviour of objects, namely non-uniform service availability. The notion of processes without errors is loosened, demanding only weak fairness in the treatment of messages.

Information and Control

Selected Papers from the 16th …, 2004