elektronická verzia publikácie - FIIT STU - Slovenská technická ...

274 Selected Studies on Software and Information Systems
Typical web navigation involves the presentation of a single graph node (web page)
at a time. However, in the Semantic Web, the presentation of multiple resources at once
seems more practical due to the different granularity of information and the availability of
both data and metadata as opposed to the Web. For example, a job offer page contains all
data about the specific job offer, while in the Semantic Web, the job offer would be
represented as several related instances, e.g. one for the job offer, one for the employer,
one for each requirement, and one for contact information.
Consequently, in Semantic Web navigation we move or modify a window, which defines
the presented resources. In the trivial case this can be reduced to moving the center of
the window, between graph nodes via edges. In the job offer example, the window would
be centered on the job offer instance and also contain other directly associated instances
(see Figure 10-1). Exploring the properties of, e.g., the employer instance would center the
window on the employer instance.
Figure 10-1. Window movement in the Semantic Web, window centers shown in grey.
If however we consider a set of job offers presented simultaneously (e.g., search results),
there is no clear node, which might be the window’s center (see Figure 10-2).
Furthermore, the Semantic Web effectively contains both data (e.g., job offer instances,
employers, requirements) and metadata (e.g., the class JobOffer, Employer and
Requirement), and a set of inference rules that can be used to reason on the available information
and infer new information. Thus, relations between resources need not be explicitly
asserted but can be inferred based on available metadata and rules enabling additional
navigation options compared to traditional web navigation.
Hence, we define Semantic Web navigation as the movement and modification of
presentation windows containing resource visualizations, based on the following of embedded
links corresponding to relations between resources.