Gellish
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Gellish is a data exchange language in which information can be expressed such that it is computer interpretable, but still system independent. Gellish is a structured subset of natural language that is suitable for information and knowledge representation and as a successor of electronic data interchange. From data modeling perspective it is a generic data model that includes domain specific knowledge and semantics.
In principle, for every natural language there is a Gellish variant that is specific for that language. For example, Gellish Dutch (Gellish Nederlands), Gellish German (Gellish Deutsch), etc.
Gellish is intended for the expression of complete and unambiguous specifications of products, facilities and processes, and for information about their purchasing, fabrication, installation, operation and maintenance and for the exchange of such information between systems, although in a system independent and computer interpretable way.
The definition of Gellish includes a large 'smart dictionary' of concepts with relations between those concepts, called STEPlib. It is called a 'smart dictionary', because the concepts are arranged in subtype-supertype hierarchy, making it a taxonomy which supports inheritance (computer science) of properties from supertype concepts to subtype concepts. Furthermore, because together with other relations between the concepts the smart dictionary is extended into an ontology (computer science). Gellish has an object-relation-object structure and therefor it includes the definition of a large number of standard relation types.
For example, in the Gellish dictionary contains definitions of concepts such as 'pump' and mass and definitions of relations such as those indicated by the phrases 'is a subtype of', 'is classified as a', has as aspect, and 'is quantified as'. This enables a computer to correctly interpret the Gellish expressions:
- centrifugal pump 'is a subtype of' pump,
- P-123 'is classified as a' centrifugal pump,
- P-123 'has as aspect' the mass of P-123,
- the mass of P-123 'is classified as a' mass,
- the mass of P-123 'is qualified as' 50 kg.
The collection of standard relation types define the kinds of facts that can be expressed in Gellish. There are mainly three groups of relation types, being:
- Relation types for relations between kinds of things (classes). They are intended for the expression of knowledge. For example, the specialization relation on the first example line above,
- Relation types for relations between individual things. They are intended for the expression of information about individual things. For example the possession of an aspect relation on the third of the above lines.
- Relation types for relations between individual things and kinds of things. They are intended for links between individual things and general concepts in the dictionary (or to private extensions of that dictionary). For example the classification and qualification relations above.
Anybody can extent the Gellish dictionary and the relation types with privately defined concepts.
A knowledge base with basic engineering knowledge is integrated with the Gellish Dictionary. That knowledge is itself expressed in Gellish. Typical the Gellish dictionary is used to select classes for classification or as standard terminology (metadata) or to harmonize data in various computer systems or as a tool in a search engine.
Gellish uses a numeric identifier for every concept. For example, 130206 (pump) and 1225 (is classified as a). This makes that the concepts are identified in a natural language independent way. A feature of that is that information and knowledge that is expressed in Gellish in one language variant can be automatically translated and presented in any other language variant for which a Gellish dictionary is available. For example, a computer can automatically express the second above Gellish expression in German as follows: - P-123 'ist klassifiziert als ein' Zentrifugalpumpe
Gellish is typically expressed in the form of a Gellish Table. A Gellish Table is a standard table that is suitable to represent any expression in the Gellish language. Its table columns are standardised. The table can be used as part of a database or as a data exchange file. A Gellish Table can be implemented in any tabular format. For example, it can be implemented as a database table, as a STEPfile (according to ISO 10303-21), or as a simple spreadsheet table.
[edit] History
Gellish is a further development of ISO 10303-221 (AP221) and ISO 15926. Gellish is an integration and extension of the concepts that are defined in both standards. The specific philosophy of spatio-temporal parts to represent dicrete time periods without change to represent time is possible, but not necessary in Gellish. A subset of the Gellish Dictionary (STEPlib) is used to create ISO 15926-4.
[edit] External links
The Gellish dictionary and knowledge base is free available under ‘open source’ conditions via sourceforge[1]. For a definition of ‘open source' see [2].
