So, in order to highlight or to abstract away certain features, the kind of metamodels that we described earlier seem to be convenient. Let me give you an example or examples of these pervasive concepts. For instance, as far when we discuss the case of logical frameworks, we have as a crucial concept the inferential machinery or consisting of rule application and hypothetical general inference. When we combine this pervasive concept with the so called Higher Order Abstract Syntax, which is a generalisation of the so-called algebraic context free grammars, well we hear we have some kind of specifically computational concept, that of course could be well described in set theory perhaps, or could be described in first order logic, but when we describe it in constructive type theory it is particularly natural.
Again in action calculi and final semantics - and final semantics would be another metamodel that we should discuss in this course - the pervasive concept, the basic concept is that of label transition system, and by simulation semantics.
Another important pervasive concept is that of term rewriting , as is the case in the metamodel consisting of graph grammars.