7/30/2019 SOWA, J. Ontology, Metadata and Semiotics

http://slidepdf.com/reader/full/sowa-j-ontology-metadata-and-semiotics 1/4

‘Ontology, Metadata and Semiotics’

John F. Sowa

Introduction

The Semantic Web can be seen as an extension of the World Wide Web (WWW). It is

a concept that has not yet been properly implemented, in which the information on the

WWW is linked up in such a way to make it more efficient (like a database that is

globally linked and is easily searchable). The Semantic Web is built on ontologies that

define the relationships between vocabularies used. It uses RDF (Resource

Description Framework), an XML-like language, as the interchange format the share

information. (Palmer, 2001)

In his article entitled ‘Ontology, Metadata and Semiotics’ (2000), Sowa attempts to

show how the analysis of meaning has many implications for web-based metadata. He

explains how the different methods of logic and ontology can be used in order to

define, relate and translate signs from one vocabulary to another. It is necessary to

make these distinctions in meaning in order for computers to be able to make links

 between ontologies used; his work has contributed greatly to the formation of the

Semantic Web. In this paper I will describe some of the main parts of Sowa’s theory

from his article as well as giving some views.

Semiotics

To make his point, Sowa primarily draws on Charles Sanders Peirce’s theories of 

semiotics. Semiotics is the study of signs. Most basically, we use signs (in the context

of this theory) as being a representation for something else. We can add detail to

metadata by ‘tagging’ on signs to create more meaning. These signs can then have

signs themselves to give another level of meaning, and so on. Peirce’s theory states

that there are three branches of semiotics – syntax (relating signs to one another),

semantics (relating signs to things in the world matching patterns of signs to related 

 patterns that occur among the things that the signs refer to) and  pragmatics (relating

signs to the agents that use them to refer to things the world). These branches of 

semiotics are what Sowa is most concerned about. He proclaims that previous

 proposals of ontologies and metadata do not include extra information that should be

7/30/2019 SOWA, J. Ontology, Metadata and Semiotics

http://slidepdf.com/reader/full/sowa-j-ontology-metadata-and-semiotics 2/4

given (such as how the term relates to the agents and to the world itself) (Sowa,

2000).

Ontologies

Sowa claims that the problem with a lot of ontologies on the web is that they ignore

many of the aspects of terms/concepts and that examples like SHOE (Simple HTML

Ontology Extensions) have categories that explain the syntax of data but not the

semantics. Without giving definitions, the tags themselves (like those using SHOE)

do not give meaning to what they are attached to.

Vocabularies

Vocabularies are ‘packages’ of details that are kept to describe things. The problem

with vocabularies is that everybody uses different terms to describe things (or use the

same terms to describe totally different things). This makes it impossible to try to

merge or share data from databases, and is one of the main reasons why identifying

meaning is so important – to distinguish what the right meaning is for the context and 

what its relationship is to other vocabularies. Methods of logic and ontology are

therefore used to make these distinctions by creating definitions for, showing relations

 between and translating these signs from one vocabulary to another.

Logic & Ontology

Peirce, mentioned earlier for his work in semiotics, studied a branch known as

semantics (or logic proper). Much of the theory on logic is very complex; Peirce used 

what he called existential graphs to show a break down of logic to its most primitive

form – resulting in five elements; existence, coreference, relation, conjunction and 

negation. These primitive elements as well as the logical operators (universal,

implication and disjunction) are used in formulas to show the definition and 

relationship between terms (Sowa, 2000).

Using Peirce’s logic along with ideas in linguistics, philosophy and artificial

intelligence, the ontology of situations and what they represent can be shown.

Controlled Natural Language

Controlled Natural Language is the closest form of language to natural language in

which knowledge extraction systems are able to automatically translate. It is not yet

7/30/2019 SOWA, J. Ontology, Metadata and Semiotics

http://slidepdf.com/reader/full/sowa-j-ontology-metadata-and-semiotics 3/4

 possible for these systems to interpret natural language – they need help from a

human editor but if knowledge extraction systems are used when forming databases,

the controlled natural language is translated to logic and a vocabulary is built for a

query system automatically (Sowa, 2000).

Issues

It seems that Sowa’s theories on metadata, semiotics and ontologies has been (and 

will continue to be) most useful in the formation of the semantic web. One of the

main reasons being because he stresses the importance of getting the right meaning

attached to terms for each instance in which they are used.

There have been a few a recent criticisms over Sowa’s theory (such as that by

Veltman (2004) in ‘Towards a Semantic Web for Culture’) in which it has been

suggested that Sowa has not considered all the issues. Veltman proposes that Sowa’s

theory does not leave room for the changing meaning of words over time or across

cultures. This was also referred to in a recent interview with Tim Berners-Lee, a

creator of the Semantic Web, in which he dismisses Veltman’s opinions as not being a

 part of the scope of the Semantic Web.

Even if, as some people believe, Sowa has missed out on some points that may or may

not be important to his theories (and for the Semantic Web), the part he has

contributed in this area of study is greatly significant and can be built upon with

further study, either by himself or by others in this field just as he has drawn from the

works of others.

7/30/2019 SOWA, J. Ontology, Metadata and Semiotics

http://slidepdf.com/reader/full/sowa-j-ontology-metadata-and-semiotics 4/4

REFERENCES

Palmer, S.B. (2001) ‘The Semantic Web: An Introduction’, Sean B. Palmer Homepage

[online], Available: http://infomesh.net/2001/swintro/ [Accessed: 20 September,

2005]

Sowa, J.F. (2000) ‘Ontology, Metadata and Semiotics’, J.F. Sowa Homepage [online],

Available: http://users.bestweb.net/~sowa/peirce/ontometa.htm [Accessed: August 27,

2005]

Sowa, J.F. (2003) ‘Ontology’, J.F. Sowa Homepage [online], Available:

http://www.jfsowa.com/ontology/index.htm [Accessed: 21 September, 2005]

Updegrove, A. (2005) ‘The Semantic Web: An Interview with Tim Berners-Lee’,

Consortium Standards Bulletin [online], Issue: June 2005, Available:

http://www.consortiuminfo.org/bulletins/semanticweb.php [Accessed: 21 September 

2005]

Veltman, K.H. (2004) Towards a Semantic Web for Culture’, Journal of Digital

Information, Vol. 4, Issue 4, Article No. 255, Available:

http://jodi.ecs.soton.ac.uk/Articles/v04/i04/Veltman [Accessed: 21 September, 2005]