The Gellish English Dictionary (also called STEPlib) is an electronic 'smart' dictionary that contains definitions of concepts, each of which is identified by a unique identifier (a number allocated by the Gellish English language manager) and can be referenced by one or more 'names', which are normal English terms, most of which can also be found in an ordinary English dictionary. All definitions satisfy the rules for proper definitions of concepts in Gellish English. This means that they not only have a textual description, but also that they have at least an explicit relation with their supertype concept(s) and thus form a consistent subtype-supertype hierarchy of concepts or Taxonomy. The Gellish Modeling Method provides guidelines for the extension of the dictionary such as with Domain Dictionaries for specialized areas and for the creation of Gellish Dictionaries in other languages. Together with the unique identifiers such other dictionaries enable automated translation of expressions.

The Gellish English Dictionary is free of charge available under Open Source conditions (through one of the Open Source Licenses) via this website.

An essential part of the definitions in the Gellish English Dictionary are the definitions of relation types. Relation types typically have 'phrases' as names, which phrases that can be used in Gellish English expressions. For example a composition relation has as name 'is a part of', which phrase can be used in a Gellish expression such as: A is a part of B. So the Gellish dictionary does not provide a definition of the separate words, like is, a, part and of, but of the whole phrase, because the phrase represents a concept. The part of the Gellish Dictionary that contains the collection of upper ontological facts (TOPini) contains the definition of the standard relation types of Gellish. They currently have 'names' and 'Gellish phrases' in English and in Dutch (Nederlands). That part also contains definitions of the kinds of the roles that are played by objects in relations of those types and it contains definitions of the types of things that can play such roles. The definitions of relation types also satisfy the rules for proper definitions of concepts in Gellish English and thus form a consistent subtype-supertype hierarchy of relation types. As all concepts in the Gellish English Dictonary, including the relation types, roles and other kinds of things, are arranged in a subtype-supertype hierarchy of concepts, the Gellish Dictionary is also a Taxonomy. The collection of upper ontological facts (TOPini) in the dictionary forms the top of that subtype-supertype hierarchy of concepts. All other concepts in the dictionary are subtypes of the generic concepts. The data in the Gellish English Dictionary are stored in a Gellish Database, as defined in the document 'The Gellish Database definition'.

The Gellish English Dictionary defines a concept by expressing a fact about the concept. That expression has the form of a specialisation relation or qualification relation. The facts are grouped in collections of facts that define domain specific subsets of the dictionary. In the current Gellish English Dictionary collections of facts can be distinguished about the following subjects:

• Generic concepts as required to define the Gellish grammar
• Documents, information and identification
• Occurrences, events, activities and processes, including physical, chemical, and business processes.
• Engineering
  • Civil, architectural and structural engineering
  • Static and heat transfer equipment engineering
  • Rotation equipment engineering
  • Transport engineering, including rail, road, air and water transport
  • Piping engineering, connection and protection materials
  • Electrical engineering
  • Control engineering, including instrumentation
  • Facilities and systems
• Geographic and marine objects
• Organisms, persons and organizations
• Aspects, characteristics, properties, qualities, and laws.
• Qualitative and quantitative aspects (standard values)
• Units of measure and scales
• Symbols and annotation
• Materials (substances), solids and fluids, elements and radiation
• Mathematics and shapes
• Roles of aspects and roles of physical objects

Every concept is a subtype of a more generic concept, up to the top concept, called anything.
Lower in the hierarchy you will find the more specialised concepts as defined in engineering standards and in proprietary standards. Further specialized concepts, such as catalogue items and manufactrer's models are again subtypes of more generalized concepts.

A smart dictionary has a number of characteristics in addition to ordinary dictionaries.
The Gellish English Dictionary is an electronic smart dictionary because it satisfies the following rules for smart dictionaries:

• It contains a definition per concept, whereas ordinary dictionaries usually provide various definitions of a term, where it is unclear whether those definitions are alternative definitions of the same concept or whether they are definitions of different concepts. Thus a smart dictionary explicitly distinguished homonyms (the same term for different concepts) and explicitly specifies which terms are used in the dictionary as true synonyms.
• It is completely arranged as a taxonomy, which is a subtype-supertype hierarchy of concepts. This means that each concept is defined as an explicit subtype of one or more supertype concepts by specialization relations (A is a specialization of B and B is a specialization of C, etc.).
• It includes also concepts with plural term names. For example: line shaft centrifugal pump.
• It defines relation types (being a special kind of concepts). These relation types enable to make computer interpretable expressions that express facts, including the expression of knowledge and information.

The fact that the Gellish English Dictionary satisfies this rule means that the Gellish Dictionary itself defines the Gellish English language. In Gellish English those relation types have names and synonyms that consist of standardised phrases. For example: the phrase 'is a part of' can be used to express the fact that A is a part of B, whereas the phrase 'can have as part a' can be used to express the knowledge that a whole of a particular kind can have as part a component of a particular kind. For example, the fact that a pump can have a bearing is expressed in Gellish English as:

pump can have as part a bearing. 

All three elements in this expression are names of standard Gellish English concepts that are defined in the Gellish English Dictionary.

• Concepts are related to other concepts in various ways by explicit relations of standardised relation types. Those additional relations express additional knowledge about the concepts. This knowledge about the concepts can be used by computers, because such knowledge about a concept is inherited by all the subtypes of that concept in the subtype hierarchy (taxonomy).
• It uses one language independent unique identifier (a natural number) to represent each concept. This enables that facts that are expressed in one language can be automatically presented by a computer in any other language for which a dictionary is available.
• It can be extended by private and proprietary concepts and terms. For example, company specific codes and proprietary knowledge. Some instructions are given in 'Proper definition of a concept'. Further instructions are given in the Gellish Dictionary Extension Manual.
• It is computer interpretable and system independent.

The Gellish dictionary contains a special collection of facts that specify how expressions of knowledge can be used to create expressions of real facts about individual things.

These are <can be realized by a> relations. Each relation of that kind relates two kinds of relations:

• a relation type that is used to express knowledge facts, being a relation type that relates two classes

with

• a relation type that is used to express real facts, being a relation type that relates two individual things

An example of such a relation is the expression of the fact that:

• a <can have as part a> relation <can be realized by a> <has as part> relation.

The collection of such relations in the Gellish Smart Dictionary specify which kind of relation type should be used when knowledge or requirements are used to create facts about individual things in an imaginary or real world. This is typically used when knowledge or requirements are turned into designs.

The following example illustrates the basic principles of knowledge-based design using Gellish. Assume that a requirement expresses that

• a pump <shall have as part a> bearing.

The above-mentioned Gellish language relations define how to apply that knowledge to create bearings for individual pumps. For example, assume that P-101 is classified as a pump, then software that is Gellish English powered can conclude that

• P-101 shall have a part X,

whereas

• X is classified as a bearing.

Such software can also derive from the Gellish Dictionary what kinds of bearings there are and from a knowledge model in Gellsh it can derive which characteristics such components normally have.

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