| Metamodel |
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In general, a metamodel is a model which describes a Domain Specific Language with which models can be expressed. There is always an implicit or explicit '''domain''' asociated to a metamodel. The activity of using metamodels for specific purpose is called metamodeling or Meta-modeling . Spelling note The recommended standard orthograph is ''metamodel'' but the alternative ''meta-model'' is also used. However the current trend seems now to write "metamodel" and mot "meta-model", "metamodeling" and not "meta-modeling". This is consistent with classical usage like Metaphysics , Metaprogramming , Metacognition , Metamathematics , Metalogic , Metalanguage , Metafiction , Metaphilosophy , Metatheory , etc. OMG metamodels The OMG produces metamodels for describing various facets of the construction of information technology systems. One of the first metamodel produced by OMG is the UML metamodel. This metamodeling activity has become much more important in the context of the Model Driven Architecture approach. In a simplified way we can state that a metamodel defines a language for writing models. For example the UML 2.1 metamodel defines a language to write UML 2.1 models. In other terms we can state that a UML 2.1 model conforms to the UML 2.1 metamodel. (The word "conforms to" is much more precise than the word "instance of" which is sometimes used by beginners to describe this relation between a model and its metamodel.). The conformance relation between a model and its metamodel is similar to the conformance relation between a program expressed in a given programming language and the grammar of the language. A metamodel may be expressed in a given formalism, for example MOF 1.4 or MOF 2.0. The only official OMG version for expressing metamodels is MOF 2.0. Unfortunately OMG has produced until now a very small number of metamodels in formats that could be really used by computers. Most of the OMG metamodels are in fact "descriptions of metamodels" expressed in .pdf or .word documents for humans only. From these descriptions tools vendors may implement their own interpretation of the metamodel in their tools, for example hard wiring the UML 1.4 metamodel in a UML CASE tools. The situation may be changing now that OMG has clearly defined that metamodels should be expressed in MOF 2.1 and serialized in XMI 2.1. We may see in the future some libraries of OMG metamodels like there are libraries of XML schemas. However there are other possible formalisms to write metamodels. Microsoft has recently defined such a formalism in their DSL tools initiative. Note that Microsoft sometimes uses the word domain model to refer to a metamodel. General metamodels Other organizations have also produced metamodels outside the strict normative context of OMG . One of them is CDIF , and the ISO is working on the 24744 International Standard metamodel. This activity is related to Model Driven Engineering . Metamodels for Therapy The Meta-model for Therapy or '''''Meta-model''''' (Bandler & Grinder, 1975 ch.3) is an explicit thera-linguistic model. The Meta-model is an explicit tool for the recovery and challenging of client models subject to the universals of human modeling: Generalization, Deletion, and Distortion. The Meta-model in Neuro-linguistic Programming (NLP) is a Model of (primarily) Linguistic models that people have. Put simply in this context, the Meta-model is a set of language patterns (from Virginia Satir, Fritz Perls and Transformational Syntax ) designed to challenge limits to a person's internal map of the world (Grinder & Bostic, 2001). Effectively the meta-model can be reduced to asking "What specifically", or "How specifically?" (Grinder & McMaster 1989) to challenge unspecified nouns or verbs. It is claimed that the Meta-model "yields a fuller representation of the client's model - the linguistic Deep Structure from which the client's initial verbal expressions or Surface Structure , were derived" (1975a p.44) by offering challenges directed at distortions, generalizations or deletions in the speaker's language (1975a Ch3). The reverse set of the meta-model is the Milton-model; a collection of artfully vague language patterns elicited from the work of Milton Erickson (1975b). Together these models form the basis for the all other NLP models. The following examples are mainly derived from within a therapeutic context, however, it is also claimed that these same patterns can be noticed and applied to any context. Distortion:Semantic Well-formedness =Example 1: Presuppositions
=Example 2: Cause and Effect (x means y, or x makes me y)
Generalisations =Example: Lack of Referential Index (people, women, men, jerks, families, ...)
Deletion =Example: Comparatives and Superlatives (best, worst, ...)
(src: Bandler & Grinder, 1975a Ch3 & Ch4) Its roots can be traced back to the work of Noam Chomsky Transformational Grammar and even further to the Nominalistic tradition of William Of Ockham . An effort unrelated by origin but going in the same direction of improving clarity of communication is the Constructed Language Loglan (and its close cousin, Lojban ). SEE ALSO
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