Difference of Ontology, Taxonomy, Folksonomy and Thesauri

The purpose of this article is to provide a little more information about taxonomies, folksonomies, ontologies and thesauri and their roles in information retrieval.

1. Background

Two indexing languages are generally used when indexing or searching for information in retrieval systems such as databases and the Internet. These are natural language and controlled vocabularies.

Controlled vocabularies are restricted lists of words that are used for indexing. The words listed in the vocabulary may be used to describe information sources in a specific subject field description is supported They explain that when the indexer or the user uses the words of the author, or words that are generally used in a subject field, to index a document or search a database, they are using natural language terms. However, when they select words from a list of possible indexing terms, they are using a controlled vocabulary.

When viewed from an information organization point of view, the objective of controlled vocabularies is to ensure consistency in indexing, tagging or categorizing. However, when viewed from an information retrieval point of view, controlled vocabularies also support users when they search for information. This means that the user does not need to think of all the possible terms that would retrieve the required information. By using terms from a specific information system’s controlled vocabulary, the users are ensured of retrieving some information that is relevant to their search.

Ontologies, thesauri, taxonomies, and folksonomies are four examples of controlled vocabularies that are relevant to this article. The following discussion therefore focuses on explaining more about these controlled vocabularies and showing how they facilitate information retrieval in an online environment.

2. Thesauri

Thesauri are described as ‘controlled vocabularies that contains index terms that are used to describe the contents of a document’. Other people extends this definition when he defines a thesaurus as a ‘controlled and dynamic vocabulary of terms that share semantic and generic relationships, and that are applied in a particular field of knowledge.’

From a functional point of view, he views a thesaurus as ‘an instrument for the control of terminology, used to transmit, in a more strict language, the language used in documents.’ The main function of a thesaurus is therefore to promote the standardization of the terminology that will be used in an information retrieval system.

3. Taxonomy

The concept ‘taxonomy’ denotes the science of classifying things. Hedden explains that the concept was traditionally used for the classification of plants and animals, such as the Linnaean classification system. However, it has lately become the preferred term for any hierarchical classification or categorization system.

The main difference between a thesaurus and a taxonomy lies in the hierarchical relationships among terms . For example, a given term in a thesaurus may or may not have a broader/narrower term relationship with another term.

Taxonomies, on the other hand, have a strict hierarchical structure. All terms in a taxonomy belong to a single large hierarchy which encompasses all concepts of a certain class, category, or aspect. Furthermore, terms in a thesaurus can have an equal relationship with other terms, as for instance with dog breeds and cat breeds. Because of the strict hierarchical structure of taxonomies, however,
there can be no equal relationships in them.

4. Folksonomies

The main difference between thesauri, ontologies, taxonomies, and folksonomies lies in the development of these vocabularies, in who creates them and their structure.

Whereas thesauri, ontologies, and taxonomies are created by experts in the field of information organization, folkson omies are created by users of information, and the language of the user becomes important in their development.

Thesauri are mainly developed by humans whereas ontologies, modern taxonomies, and folksonomies are computer generated. Lastly, folksonomies reflect no hierarchical structure and there are no directly specified parent–child like relationships. These are merely a set of terms that are used by a group of people to describe information sources.

5. Ontology

Ontologies are catalogues which capture human knowledge based on common sense; as groups of concepts; a general framework which can display coherent organization; the marriage of symbols used in natural language and the entities that they represent in the real world. However, An ontology ‘is the systematic description of a specific domain in accordance with the entities and processes that allow the description of “all” things and processes’. Or say ontologies as ‘a level of abstraction of data models, analogous to hierarchical and relational models.’

It is important to note that irrespective of how relationship pairs in ontologies are determined,
the structure of ontologies is aimed at providing an order and a relation of terms which are based on certain characteristics and properties.

6 Someone’s remark

“A taxonomy is just a classification of things. They are usually hierarchical. They do two things: give exact names for everything you’re dealing with (your ‘domain’) and show which things are parts of other things (sometimes called parent-child relationships, sometimes called broader-narrower).”

" An ontology is like a taxonomy in that it is going to contain all the entities in your domain, and show the relationships they have to each other. However, it does more: it has strict, formal rules about those relationships that let you make meaningful, precise statements about your entities/relationships."

“Folksonomy is essentially what you see on del.icio.us or flickr. It’s in many ways the exact opposite of a taxonomy in that: a. Folksonomies are flat (that is, they have no hierarchy, and show no parent-child relationships) b. Folksonomies are completely uncontrolled (part of making a taxonomy is deciding what the names of your entities are, but in a folksonomy, there can be a thousand different words for the same thing) Any relationships you see in a folksonomy have to be derived mathematically (statistical clustering). However, a folksonomy is like a taxonomy in that they share the same purpose: classification. A lot of debate is going on right now about which is better, though of course the answer is that you use them for different purposes. It’s nice to have both.”