This page intends to cover some of the technologies which are involved in the Semantic Web and the underlying principles which cover Ontologies in the context of e-Learning. This will therefore look at how the technologies are affecting e-Learning applications, and how e-Learning is driving further research in these technologies.

--By Lara--

What is the semantic web?
The term semantic web refers to a web that makes sense of the data it presents to the user. Hence the information that the user is presented with, is not only being understood by the ‘human’. It has also been understood and interpreted by the web in order to present the most relevant options to the user. The standard web was already understandable by human beings and was also read by machines (Lassila, 1998, as cited in Ghaleb et al 2006). The semantic web differs from the original web in that it also makes sense to machines (Ghaleb et al, 2006). This is greatly advantageous to us since the semantic web, envisioned by Tim Berners-Lee, means that data on the web can be categorised, searched and fetched according to this category by intelligent agents (McIlraith, Son & Zeng, 2001, as cited in Ghaleb et al, 2006).

The image below shows the difference between Web 1.0, Web 2.0 and the Semantic Web highlighting the main differences between the conventional web and the semantic web mentioned above.

The difference between the web and the semantic web
The difference between the web and the semantic web



Re-use and sharing of knowledge
If data on the web now makes sense to both humans and machines alike, then knowledge can be more easily shared worldwide. This is done through the use of amalgamating e-Learning and Semantic Web technologies, namely learning objects and ontologies (Sicilia & Garcia, 2005). Both of these technologies describe knowledge in some standardised form, the former one to describe the particular learning object and the latter one to tag web resources (Fensel, 2002, as cited in Sicilia & Garcia, 2005). Hence this makes it easier to re-use and share knowledge.

Ontologies and the Semantic Web
As mentioned above, data on the web uses ontologies to describe them in some standard from. This description, or tagging, is done by some form of XML based language (Klein, 2001, as cited in Ghaleb et al, 2006). Various such XML-based languages have emerged over the years. OWL (Web Ontology Language) is one such language which emerged in 2004, and which was recommended by the W3C (W3C, as cited in Ghaleb et al, 2006). Ontologies, which “define terms and their relationships” (Ghaleb et al, 2006), do not alone make up the semantic web. Semantic markup also helps to develop the semantic web. This building block of the semantic web is a set of comments about defined ontologies and also provide pointers to the whole set of ontologies (Ghaleb et al, 2006). Web pages contain these semantic mark ups, which according to Ghaleb et al (2006) make them “computer-interpretable, use-apparent, and agent-ready”. These machine-understandable web pages can now be accessed by semantic web services and fetch information for the user.


The image below shows a graph depicting semantic web services and the semantic web. The shaded blue area shows the capabilities of semantic web on its own (the Knowledge Management area). These 'limits' of semantic web can be addressed by combining the semantic web knowledge management area, together with semantic web services which allows for Enterprise Application Integration. Together these allow for the higher facilities such as composing and monitoring services. Furthermore they also are able to address e-challenges. (Cefriel, Semantic Web Activities)

external image img_Impact-vs-risk_v2.gif&sa=X&ei=c3sJT9OGB-aA4gSo5tGNCA&ved=0CAoQ8wc&usg=AFQjCNGVcZdw2LmxkxMKQir-_QpKC3GyNA



Final Comments
I believe that the semantic web is greatly helpful to all since the information on the web can be categorised and not simply all put into one place, without making head or tail of how some information is related to the rest. If all the information that is placed on the web is tagged in some standardised way, it would mean more accurate and relevant information searches for one. In relation to e-learning, it would also mean that learning objects can be shared and found more easily in this way. This would make sharing of resources more feasible and accessible and e-learning would surely continue to flourish.

References
Cefriel, Semantic Web Activities. (n.d.). Semantic Web Activities. Retrieved January 7, 2012, from http://swa.cefriel.it/

Ghaleb, F., Daoud, S., Hasna, A., ALJa’am, J. M., El-Seoud, S. A., El-Sofany, H. (2006, August). E-learning model based on semantic web technology. International Journal of Computing and Information Sciences, 4(2). Retrieved January 7, 2012, from https://vle.um.edu.mt/vle1112/file.php/2628/Literature/pp63-71_1_Copy.pdf
Jose, A. (2009, May 23). What is the semantic web? [Msg 1]. Message posted to http://www.rockingteam.com/2009/05/what-is-semantic-web/

Sicilia, M., & Garcia, E. (2005). On the convergence of Formal ontologies and standardized e-learning. International Journal of Distance Education Technologies (IJDET), 3(2). Retrieved January 7, 2012, from https://vle.um.edu.mt/vle1112/file.php/2628/Literature/ontologies_elearning.pdf
------By Elaine -----

1. What are Ontologies?

Ghaleb et al. (2006) describe ontology as ‘comprising a set of knowledge terms, including the vocabulary, the semantic interconnections, and some simple rules of inference and logic for some particular topic.’ When ontologies are applied to the web, they are creating the Semantic web.

Ontologies provide the necessary framework around which knowledge bases should be built and set grounds for developing reusable Web-contents Web-services and applications,

The use of ontologies for describing learning contents enable the extension of current
specifications with additional relations and axioms among metadata items, without breaking their original semantics. (Sicilia et al., )

Therefore, it facilitates knowledge sharing and reuse, that is the common understanding of various contents that reaches across people and applications.


Ontology Desciption Languages


Seeing an ontology form the technical point of view, it is a text-based reference knowledge, put somewhere on the Web for agents. There are lower-level ontology representation such as XML and RDF, and higher-level agents,such as OIL and OWL, which are build on top of the lower level.


In Figure 1, we can see the different ontology languages classification. (Todorova & Stefanov, 2006). The most ontology languages classification that interest us the most when talking about eLearning and Semetic web are the Web-based Languages and Rule-based Languages.
external image sguvb_nemPERLc8mZtoHGcOYPZbeOpCBody_d84BKwXSsaukqQWESkDPlwkol1ZlndAqEwMM1VIItfv4lMbgQ3mQO_FFyNpviADWB26w9bWb3JjgJg8


Figure 1: Ontology Languages Classification




2. How they are formed


Ontology formalisations are based on specialised logics which are designed for expressiveness and computational efficiency. Kabel (2001) state that they could be used to provide a richer), semantic-enabled computation framework for metadata-based e-Learning.In fact, its’ use of formal ontologies can be richer not only by applying standardised metadata, but in their framework and subsequently in it use by automated tools.

Principles like “modularization” and “extensibility” are addressed by the use of open XML-based formats prepared for the Web (Fensel, 2002a), while the principle of “refinement” is formally defined by the logical interpretation of subsumption. The practicalities of building application profiles for particular usages can be realised by means of constructing specialised ontologies from more general ones, adding specialised terms.


Problems

But the integration of formal ontologies with the paradigm of learning objects poses several problems that have not been addressed yet. These problems can be roughly categorised in technical and organizational issues.

Technical issues include the practicalities of expressing the structure, properties and prospective contexts of use of learning objects as description-logic expressions, and thus entail a notion of what a complete and consistent metadata record should be.

Organizational issues are those that would eventually be caused by the adoption of ontology based learning objects in organizations, as part of an integrated value process. These issues include the need for specific user interfaces, the provision of intra-organization conceptualizations coherent with shared ones and new approaches for the assessment of the quality of metadata records.


3. How they can be applied to eLearning

eLearning and Semetic web intersect by converging two key concepts learning objects and ontologies.
  • Learning objects are focused on instructional design with the notion of re-usability.

  • Ontologies are logic-based consensual knowledge representations that are used as a means to annotate as a means to annotate Web resources. This will provide a semantic meaning which become more enablers for the knowledge management tools and processors.


Stojanovic et al. (2001) provide a comprehensive list of high-level benefits of using Semantic Web technology for eLearning, and they also provide a structure made up of three ontologies that address the description of the topics of the learning material (content), the form of presentation (context) and the composition of learning materials (structure).

Sampson et al.(2004) anticipate that Ontologies and Semetic Web will influence eLearning systems. The. The key structures will be on formal taxonomies expressed as examples with the help of Web Ontology languages such as RDFS and OWL and rules expressed with the help of web rule language RuleML. Together they will enable the representation and dynamic construction sharing and reusablilty of learning content.


References

C. Todorova & K. Stefanov (2006) Selection and use of domain ontologies in Learning Networks for LifelongCompetence Development. In Learning Networks for Lifelong Competence Development (editors R. Koper and K. Stefanov), Sofia, Bulgaria, pp. 11-17.

Kabel, S. (2001). The added value of ontology-based instructional markup. Proceedings of AIED, 496-499.


Sampson, D. G., Lytras, M. D., Wagner, G., & Diaz, P. (2004). Ontologies and the Semantic Web for E-learning. Educational Technology & Society, 7 (4), 26-28.