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10
SEMANTIC-BASED NAVIGATION
IN OPEN SPACES
Michal Tvarožek
The Web is a large open information space, where large means that the information space
contains many – millions or even billions of information artifacts, while open means that
virtually anyone can modify its contents in a more or less unrestricted, syntactically correct
way.
In general, navigation can be defined as movement and orientation in an information
space. Web navigation can be defined more specifically as “the activity of following links
and browsing web pages” (Levene & Wheeldon, 2004), where movement corresponds to
the following of links, and orientation corresponds to the knowledge of one’s position and
selection of links to follow. In practice, the navigation problem (i.e., users getting lost) and
issues concerning information overload significantly impair search and navigation experience
for many users.
Due to these problems and properties of the Web, truly effective navigation means
for the web environment have yet to be realized. Adaptive navigation aims to address
these issues by adapting the hyperlinks and their associated visualization. For example, it
may add new links to related pages, annotate links with additional information, highlight
relevant links or remove broken or unimportant links.
We describe the similarities and differences between Web and Semantic web navigation
also from the graph perspective, and introduce navigation as means for search. Next,
we outline the concept and goals of adaptive navigation, while also providing an overview
of existing navigation types, navigation and orientation tools, and visualization options
and approaches. Lastly, we conclude this section with a comparative overview of existing
navigation and visualization solutions.
10.1 Web Navigation vs. Semantic Web Navigation
Since the Web can be seen as a network of documents linked via hyperlinks, it can be
represented as a directed graph where nodes represent documents (information artifacts)
and edges represent hyperlinks. Similarly, the Semantic Web is a network of resources
linked via relations, which can also be represented via a directed graph. Thus, web navigation
is the process of moving via edges from one graph node to another.
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