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Title: Linking the semantics of a multithreaded discrete event simulation language
Author: Zhu, Huibiao
ISNI:       0000 0001 3584 0972
Awarding Body: London South Bank University
Current Institution: London South Bank University
Date of Award: 2005
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Verilog is a hardware description language (HDL) that has been standardized and widely used in industry. MDESL is a Verilog-like language, which is a multithreaded discrete event simulation language. The language contains interesting features such as event-driven computation and sharedvariable concurrency. For ensuring correctness of hardware design, precise understanding of the language based on semantics is very important. There are several semantics for the language and the consistency of these semantics is challenging. This dissertation focuses on the semantics of MDESL and their linking theory. The denotational semantics of MDESL has been formalized under a discrete time model. In order to deal with the shared-variable feature, the behaviour of a process is described in terms of a trace of snapshots. The operational semantics has been formalised as a set of transition rules, which is expressed in the notation of SOS( Structural Operational Semantics. A prototype of the operational semantics has been developed using Prolog. The operational semantics is fully compositional, which can be linked with the denotational semantics. Algebraic properties have been studied, which can be used in support of program simplification and optimization. The program properties can be proved by two approaches: denotational semantics and operational semantics (via bisimulation). Two approaches have been proposed in order to formally link operational semantics with denotational semantics. The first approach is to derive denotational semantics from operational semantics. The second is the inverse approach, which is to derive operational semantics from denotational semantics. In order to represent the denotational view of a transition, the concept of transition condition and phase semantics has been defined for each type of transition and applied in both approaches. Regarding the operational semantics, two significant questions have been investigated: soundness and completeness. The understanding of these two aspects is based on the denotational semantics. The operational semantics has been proved to be sound and complete. The aspect of non-redundancy for operational semantics has also been discussed. How the algebraic semantics relates with the operational semantics and denotational semantics has also been explored. The approach starts from the algebraic semantics, where every program is expressed as a healthy normal form of guarded choice. A transition system (i. e., operational semantics) for MDESL has been derived and the equivalence between the derived transition system and the derivation strategy has been proved. The healthy normal form has also been derived back from the transition system. The denotational semantics for finite programs has also been derived from the healthy normal form. The results achieved here are not limited to MDESL. The approaches taken may also be applicable to some other languages with different programming features.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available