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Formal Semantics for PLEX


Research group:

Publication Type:

Conference/Workshop Paper


17th Nordic Workshop on Programming Theory, NWPT05


In any system with shared data and concurrent (or independent) activities, there is a need to guarantee exclusive access to the shared data. A system designed for parallel processing handles this by synchronizing the access to the shared data. But if parallel processing, and synchronization, wasn’t an issue at the time of designing the system, non-preemptive execution on a single-processor architecture, automatically guarantees exclusive access to the shared data. The problem arises when the singleprocessor architecture is to be replaced by a multi-processor ditto. At this point, the nonpreemptive execution does not protect the shared data any longer, since independent parts, still executed in a non-preemptive fashion, but on different processors, may now access and update the same data concurrently. The question is: How is such a system to be parallelized? A naive solution would be to re-implement the system, but since a legacy software system may contain several million lines of code, this solution is infeasible. A more reasonable solution would be criteria that ensures when functional equivalence, in some central aspect, is preserved for the existing software when it, is executed on a parallel architecture. To ensure the correctness of such criteria, the formal semantics of the language in question need to be considered.


author = {Johan Lindhult and Bj{\"o}rn Lisper},
title = {Formal Semantics for PLEX},
pages = {65--66},
month = {October},
year = {2005},
booktitle = {17th Nordic Workshop on Programming Theory, NWPT05},
url = {}