Gruninger and Fox Methodology

This ontology development methodology was proposed by Gruninger and Fox (1995) and consists of following six steps.

 Motivating Scenario

 Informal Competency Questions

 First Order Logic: Terminology

 Formal Competency Questions

 First Order Logic: Axioms

 Completeness Theorem

2.4.1.2.1 Motivating Scenario

The need to develop ontologies arises from the motivating scenarios particularly drawn by the industrial problems. These industrial problems normally exist in the form of story problems or examples which were not properly dealt with by the existing ontologies. Hence motivating scenario form the first step to create new ontology or extending the existing ontology.

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2.4.1.2.2 Informal Competency Questions

The informal competency questions are a set of queries (triggered by the motivating scenario) which need to be answered by the new ontology. The term informal suggests that these queries/questions have not been yet represented in a formal ontology language. The relationship between the motivating scenario and the informal competency questions help in evaluating the new/extended ontology. Based on this evaluation the need for the new ontology or extension ontology can be determined.

2.4.1.2.3 First Order Logic: Terminology

Once the informal competency questions have been proposed the terminology of ontology should be expressed in first-order logic. This terminology of ontology results from the previous step when competency questions/queries were proposed for a new or extended ontology. The very first step in formally specifying the ontology terminology is to identify the objects in the domain of interest. These objects are described by variables and constants in the ontology language and subsequently relations between these objects can be defined.

2.4.1.2.4 Formal Competency Questions

After the competency questions are informally defined and terminology of ontology is defined, the competency questions are formally defined. It is important to realize that the terminology of the ontology should have all the terms used in the formal competency questions. The formal competency questions help to evaluate the proposed new or extension ontologies.

2.4.1.2.5 First Order Logic: Axioms

The first order logic axioms define ontological terms and helps to apply constraints on these terms. Axioms constitute an essential part of the ontology and describe semantics of the terms used in first order logic. Defining axioms is the most difficult part of defining ontologies however the formal competency

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questions help to specify these axioms. The expressiveness of axioms is determined by their ability to represent competency questions e.g. if a set of axioms completely represent competency question as compared to the other one then we can say that first set of axioms is more expressive than the latter one.

2.4.1.2.6 Completeness Theorem

Once the competency questions are formally defined, the conditions which fulfil the solutions of competency questions are specified.

2.4.1.3 METHONTOLOGY

METHONTOLOGY a methodology for ontology development was proposed by Ferndndez et al. (1997) and was developed in Artificial Intelligence Lab (Ontology Engineering Group) at Technical University of Madrid. This methodology was created in the domain of chemicals however it can be used as reference for other domains as well. Main steps in this methodology are as follows:

 Specification

 Knowledge Acquisition

 Conceptualisation

 Integration

 Implementation

 Evaluation

 Documentation

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2.4.1.3.1 Specification

The aim of this step is to create a specification document expressed in natural language using the competency questions or by using a set of intermediate concept representations. This methodology recommends that the specification should include the purpose of ontology, the level of formality required, and the scope of the ontology. The ontology specification document should have conciseness, partial completeness and consistency in it.

2.4.1.3.2 Knowledge Acquisition

The knowledge acquisition phase runs parallel to the specification phase where all the relevant information is acquired using the expert guidance, books, figures, and by consulting similar ontologies. Relevant information from these resources is elucidated by using methods like brainstorming, interviews and knowledge acquisition tools. In METHONTOLOGY, the ontology developers have used a range of techniques during knowledge acquisition phase which include interviews with experts, informal and formal text analysis.

2.4.1.3.3 Conceptualisation

In conceptualisation phase, domain knowledge is structured using the domain vocabulary identified in the specification phase. A Glossary of Terms (GT) that includes concepts, and verbs, is developed to capture all the applicable domain knowledge with its meanings. Part of the GT is identified from the specification document while others are identified as the ontology development process progresses. On the basis of concepts and verbs rules are built which collects the domain knowledge.

2.4.1.3.4 Integration

Integration refers to reusing and interlinking the terms used in current ontology with the existing ontologies to expedite ontology development process. The existing meta-ontologies must be explored to align the definitions used in

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current ontology. For this purpose, the ontology developers should explore relevant libraries of ontologies which provide coherent semantics.

2.4.1.3.5 Implementation

The ontology implementation phase requires ontology development environment which can support the formal ontology. The ontology development environment should be able, to display lexical and syntactic errors, to provide an editor to modify the definitions, a browser to look for library of the ontology and other similar functions to facilitate the implementation process.

2.4.1.3.6 Evaluation

The purpose of evaluation phase in METHONTOLOGY is to make “technical judgement of ontologies, their software environments and documentations” with reference to the specification document. The output of this phase entails various evaluation documents listing the techniques of evaluation and the errors found during each step of this methodology.

2.4.1.3.7 Documentation

This phase requires the documentation of the developed ontology.

METHONTOLOGY necessitates the documentation phase in the ontology development cycle because of the fact that no consensual guidelines are available to facilitate the developers in documenting the ontology development process.