The purpose of PSL-Core is to axiomatise a set of intuitive semantic primitives that is adequate for describing the fundamental concepts of manufacturing processes. Consequently, this characterization of basic processes makes few assumptions about their nature beyond what is needed for describing those processes, and the Core is therefore rather weak in terms of logical expressiveness. In particular, PSL-Core is not strong enough to provide definitions of the many auxiliary notions that become necessary to describe all intuitions about manufacturing processes.
To supplement the concepts of PSL-Core, the ontology includes a set of extensions that introduce new terminology. An PSL extension provides the logical expressiveness to express information involving concepts that are not explicitly specified in PSL-Core.
For each symbol in the nonlogical lexicon of an extension of PSL, there exist one or more axioms, written in KIF, that constrain its interpretation. A distinction is drawn between definitional and nondefinitional extensions of PSL-Core. A definitional extension is an extension whose nonlogical lexicon can be completely defined in terms of PSL-Core. Definitional extensions add no new expressive power to PSL-Core. Nondefinitional extensions (also called core theories) are extensions of PSL-Core that involve at least one new primitive not contained in PSL-Core.
All extensions within PSL must be consistent extensions of PSL-Core, and may be consistent extensions of other PSL extensions. However, not all extensions within PSL need be mutually consistent.
The organization of the extensions below reflects the Parts within the proposed standard ISO 18629.
Last Updated: Wednesday, 18-September-2002 11:27:07
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