**2.5 Ontolingua**

*Ontological Analyses in Science, Technology and Informatics*

SHOE as an example; it can divide into two steps as follows:

compatible-with = "version list" URL = "location">

**Define an ontology**

**Use an existing XOL ontology**

with = "version list">

declarative semantics.

knowledge base query or manipulation.

**2.2 KIF**

**2.3 GFP**

SHOE is a specification that describes an extension to HTML, which provides a way to semantically describe important information about HTML or other web documents [1]. It offers a hierarchical classification mechanism for HTML documents and non-HTML documents or subsections of HTML documents. The intent of this specification is to make it possible for user agents, robots, and so on, to gather truly meaningful information about web pages and documents, enabling significantly better search mechanisms and knowledge gathering. Let us take the

<Ontology "ontology-unique-name" version = "1.0" backward-compatible-

<Ontology-extends "ontology-unique-name" version = "Version" backward-

This is a simple way to define ontologies containing rules. Ontology simply means an ISA hierarchy of categories and a set of relations between these categories in this SHOE specification. Categories will also inherit relations defined in parent categories. However, this specification does not as yet define any other forms of relationships (transitive closures, inverses, negations, etc.) and use the complicated

and human-unreadable Hypertext Markup Language as the basic syntax.

At the same time, first knowledge interchange format was proposed by American National Standard (dpANS). Though many ontology languages are still developed, researcher in Standard University begins to design a language for the intercommunication. Interchange of knowledge or ontology thought out disparate computer systems (different programmers, different languages, and other discrepancy in interknowledge sharing). KIF language is logically comprehensive with

In addition to these essential features, KIF is designed to maximize the implementability and readability. KIF provides a declarative language for describing knowledge. As a pure specification language, KIF does not include commands for

GFP is first motivated by the hierarchic framework design of frame-based knowledge representation systems (FRSs) used at the Stanford Knowledge Systems Laboratory for accessing Cyc, KEE, and Epikit [8]. FRSs can contain all of the database systems and knowledge systems or other frame-like projects. It is complementally developed to support knowledge sharing. It specifies a new protocol, Generic Frame Protocol (GFP), for connecting knowledge bases (KBs) in FRSs. In more detail, it provides numbers of operations to formulate a general interface for all of the FRSs. Also, complementary tools were also produced to keep independent and general operation generation. GFP shows well compatibility between different languages, including Java, C (client implementation only), and Common Lisp.

After GFP coming out, OKBC, a new protocol called Open Knowledge Base Connectivity, has taken it up in more implicit knowledge model and knowledge

Thus, some format conversations of languages are also needed.

**38**

**2.4 OKBC**

Ontolingua, which accompanies with different ontology languages breaking out, can serve as a basic framework to support open or domain knowledge sharing system. The syntax of Ontolingua definition is based on GFP. It is motivated by the need of Summer Ontology Project, a pilot study in which researchers from several groups and institutions met weekly to design ontology of terms used in modeling electromechanical devices. **Figure 1** depicts the structure of Ontolingua.

**Figure 1.** *The structure of Ontolingua.*

**Figure 2.** *The structure of OML.*

At first, authors and editors will publish their ontology or maintain an ontology with a HTTP protocol connection. Users may access the different defined ontologies in Ontology Library, for example, ontologies, product ontologies, document ontologies, commerce ontologies, and agent knowledge. Beside the ontology editors or editors, some remote application may also need to duly connect this ontology library in GFP protocol to exchange or manipulate ontology. When it comes to standalone application, interface definition language with a specific and functional method will retrieve an ontology batch from ontology library. Ontolingua keeps a balance in generalization expressed GRP protocol and selectivity in some standalone application by own interface definition language (IDL).

Ontolingua can thereby be shared by multiple user and research groups using their own favorite representation systems and can be easily ported from system to system. The syntax of Ontolingua definition is simplified with some class name, argument, and documentation string.

### **2.6 OML**

XOL is more similar to Ontolingua. However, Ontolingua using OKBC is frame-based design and less semantic expression. At the same time, a separate set of researchers is pursuing a concept-role restriction language—OML. Ontology markup language (OML) is an adaptive change language based on SHOE. Earlier versions of OML were basically an Extensive Markup Language (XML) translation of the SHOE language with suitable changes and improvements. Common elements existing in OML can be described by paraphrasing the SHOE documentation to some degree. Now OML is highly RDF Schemas compatible, although it has own solution within the namespace problem. More importantly, OML has incorporated own elements and expressiveness of conceptual graphs. As shown in **Figure 2**, by declaring and registering operation, OML can be seen as a bridging connection between Ontology and Collection, which reflects more extent and incidence of ontology.

#### **2.7 An ontology exchange language in XML format: XOL**

With the development of the relative language, protocol and definition, and the need of an Evaluation of Ontology Exchange Languages for bioinformatics, several researchers on the evaluation team are currently developing a specification of XML expression of Ontolingua using OKBC, while a separate set of researchers is pursuing a frame-based version of OML. However, Ontolingua first uses a Lisp-based syntax (rather than HTML-based or XML-based), which leads to become hard to develop and maintain, though the semantics of OKBC-Lite are extremely similar to the semantics of Ontolingua. At this background, XOL was first published in 1999.

**41**

**Table 1.**

*The classes of XOL [2].*

*Ontology Language XOL Used for Cross-Application Communication*

The usages of XOL are based on frame-based approach. In this part, we will

Classes are composed of entities. Entity that is not the class but an instance of a class or multiple classes is said to be Individual. Classes and Individual distinguish by whether entity is a class of another entity or not. Class entity male or class entity female is the subclass of another class entity human, a man called Joe is an Individual entity of the class entity. The following Class is the basic Class descrip-

Slot is common property of each class or instance. The attribute "Documentation" of class has an introduction to this class. When it comes to the specific KB, slot may

SYMBOL The class of all symbols

classes

INTEGER A subclass of NUMBER

LIST The class of all lists

A subclass of THING

A subclass of INDIVIDUAL

Slots on slots, as shown in **Table 2**, are the several restrictions or declarations defined to this slot. Although it may be inherited from other KB or class, restriction

CLASS The class of all classes INDIVIDUAL The class of all entities that are not

divide into "own slot" in this KB or "template slot" inheriting from class.

**Name Description Name Description**

*DOI: http://dx.doi.org/10.5772/intechopen.91385*

introduce the constituent part and its usage mode.

• Double-precision floating point numbers

tion defined in the OKBC-Lite (**Table 1**).

or declaration on slots in this XOL file is exclusive.

The superclass of every class

A subclass of INDIVIDUAL

A subclass of INDIVIDUAL

THING The root of the class hierarchy

NUMBER The class of all numbers

STRING The class of all text strings

**3. The usages of XOL**

**3.1 Basic data type**

• Floating point numbers

• Integer

• Strings

• Boolean

**3.3 Slots on slots**

**3.2 Classes**

• Name of class
