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Semantic-Based Navigation in Open Spaces 281
− Direct guidance is a technique that recommends the next link or sequence of links,
which should be visited by a user, usually via a “next” button. It is often used in educational
systems, where the next link to be visited is determined based on user knowledge
about specific concepts.
− Adaptive link sorting changes the order of existing links. Until now, it was mostly used
in closed information spaces but was not very well accepted by users who were confused
by the constantly changing order of links, which the users expected at their
original locations. However, adaptive link sorting might be employed in open information
spaces, which often change by their sole definition. Moreover, in large information
spaces, sorting is the only sensible means of finding the required information
and is used by all search engines. Consequently, adaptive link sorting and link generation
should not have adverse affects on user experience in large open information
spaces.
− Adaptive link generation adds new links to related resources, e.g., based on the results
of data mining techniques.
− Adaptive link hiding can be subdivided into these techniques:
o Link hiding, when links are clickable but look like normal text.
o Link disabling, when links are not clickable yet look like normal text; used for contextual
links.
o Link removal, when links are physically removed; used for non-contextual links.
− Adaptive link annotation, as perhaps the most used technique, adds additional information
to selected links, whose purpose is to more closely describe the target web pages
thus helping the user to decide which link to follow next.
− Map adaptation adapts the local or global sitemap respectively.
We devised a method for adaptive faceted browsing in the Semantic Web and developed
a prototype adaptive faceted semantic browser – Factic (Tvarožek & Bieliková, 2007). Figure
10-8 illustrates examples of common adaptation techniques on a sample GUI from
Factic. We focused on the adaptation of facets and restrictions (left), which includes
− direct guidance via recommended restrictions (green background).
− link generation – all links for restrictions are generated (left).
− link sorting – individual facets are sorted by relevance, restrictions are sorted alphabetically
(left).
− link annotation via tooltips and traffic light colors for individual restrictions and background
color for facets (left).
− link hiding by hiding irrelevant facets, which are available on demand (left).
10.5 Navigation and Orientation Tools
The most common means for navigation on the Web is the web browser, which retrieves,
renders and displays web pages, and allows users to navigate the Web by means of following
links.