ABOUT ONE METHOD OF DOMAIN ANALYSIS



About one method of domain analysis.

Key words: domain analysis.

Opportunities of modern technologies allow formalizing existing knowledge and automating the process of their treatment. Recently, attention is directed to the creation of ontologies - electronic information resources used for the automation of the educational process. At the formal level ontology is a system consisting of a set of concepts and a set of assertions about these concepts, on the basis of which it is possible to describe the classes and relations of a function and theory. One of the most famous ontology definitions formulated by T. Gruber, is as follows: "ontology as an "explicit specification of a conceptualization," which is, in turn, "the objects, concepts, and other entities that are presumed to exist in some area of interest and the relationships that hold among them." A lot of different definitions of ontology was formulated. However, some definitions reflect the ways in which the authors build and use ontologies, for example: "Ontology is a hierarchically structured set of terms to describe the subject area, which can be used as a reference framework for the knowledge base".

Development of the ontological modeling knowledge systems directly linked to the World Wide Web, as search and using the right information is getting more difficult, time-consuming and inefficient, since poorly formalized knowledge in a form suitable for processing with software agents. Currently, the knowledge data base created with the help of this technology successfully and widely applied, as well as developed. The main focus is the transition from the data storage and processing to the accumulation and processing of knowledge. And one of the approaches for solving the above problem is now the transition from the classical Internet (WWW) to Semantic Web.

The idea of the Semantic Web was firstly proclaimed in 2001 by creator WWW, Tim Berners-Lee. Its essence is to automate "smart" processing tasks of values (in the semantic sense) of various resources available on the web. Processing and exchange of information shouldn't be engaged by people but with special agents (program placed on the Web). But in order to communicate with each other, agents must have a common (shared by all) formal presentation of the general, explicit and formal specification of values.

The basic Semantic Web technologies are:

1. XML - eXtensible Markup Language

2. RDF - Resource Description Framework

3. OWL - Web Ontology language

To create a common conceptual format of presentation and interpretation of knowledge it is necessary to agree not only on common terminology and terms, but also about the language of submission of this knowledge.

Tim Berners-Lee proposed to separately developing of the syntax and semantics of the language to describe human knowledge.

XML language defines a set of rules of document markup in a readable form for humans and machines simultaneously. XML is a subset of Standard Generalized Markup Language (SGML). XML allows developers to create their own hidden tags, which a web page can be provided with. Thus using the XML documents can be provided with an arbitrary structure, but XML does not report semantic content of the document.

RDF is a language reporting of WWW resources, which is an XML specification; It is used to represent the metadata associated with the web resources. A special feature is that the basic element of RDF model is a triplet: a resource (subject) is linked to another resource (object) by a third resource - arc - which is the predicate. In this case, it is said that "the subject tends to predicate the value of the object", and at the beginning of each RDF-document is a list of links to ontology (namespaces). The system of classes and RDF scheme properties similar to the type system of object-oriented programming languages, such as Java, but it differs from many other systems, the consequence of which is to focus on software, as the ultimate consumer of information and the possibility to carry automatic processing of Web-resources. The semantic extension of RDF - RDFS defines the classes, properties and other resources, is a description language of dictionaries for RDF.

OWL (Web Ontology Language) is a representation language of ontologies on the Web. In fact, it is a dictionary expanding the set of terms defined with RDFS. OWL ontology may include descriptions of classes, properties and their instances. Creating of OWL is a response to the need for knowledge representation on the Web into a uniform format. Historically, the predecessor of OWL was the language DAML + OIL, which united two initiatives: DAML project (DARPA Agent Markup Language) and OIL project (Ontology Inference Layer). The earliest project of Ontology presentation on the Web was SHOE (Simple HTML Ontology Extensions).

OWL language has 3 dialects (a subset of terms).

 OWL Lite has the least expressive power from all, but it may be enough for simple tasks.

 OWL DL has an expressive power equivalent of descriptive logic (solvable part of the first-order predicate logic).

 OWL Full is the most developed dialect. It is RDF Equivalent.

There are many different ontology editors - ie, applications that allow you to create and modify ontologies. Here are some of them: Protégé Desktop, WebProtege, OilEd, WebOnto, ODE.

The most popular editor is the Protégé, having an open, easily extensible architecture by supporting the expansion of the functionality modules.

In this editor following tabs are available:

 Active Ontology - displays metadata, data on imports, metric data of an ontology

 Entities - displays all the classes, properties and instances of an ontology

 Classes  is specialized to work with classes

 Object Properties - allows to work with object properties of an ontology

 Data Properties - allows to work with typed properties of an ontology

 Individuals - allows to work with instances of an ontology

 OWL Viz is the tab to work with the OwlViz plugin

 DL Query - allows to receive information from an ontology that meet the requested criteria