Adaptive Navigation Support

1. Adaptive Navigation Support Peter Brusilovsky

2. Index • What is adaptive navigation support? • History behind adaptive navigation support • Adaptation technologies that provide adaptive navigation support • Adaptation mechanisms for adaptive navigation support • Adaptive navigation support beyond hypermedia

3. What is Adaptive Navigation Support? • Specific group of technologies that help the user navigate through the hyperspace by adapting to his goals, preferences and knowledge • The motivation is to • Help the user achieve the goals faster • Reduce navigation overhead • Increase user’s satisfaction with the system • Used in application areas ranging from e-commerce to e-learning and in virtual museums

5. History behind adaptive navigation support • Research started in early 1990’s • Problems related to inefficient navigation and the problem of being lost in the hypermedia • Early navigation support technologies used manual indexing and provided navigation support within a closed corpus of documents • The Web provided an attractive platform for adaptive hypermedia applications • Research got divided into two parts: • Using the known adaptive hypermedia technologies in the new web context • Developing new technologies and new mechanisms • Focus on exploring real world systems rather than lab level systems

6. Adaptation Technologies • Direct guidance • Link Ordering • Link Hiding • Link Annotation • Link Generation

7. Direct Guidance • Suggests the next best page for the user to visit according to the user’s goal, knowledge or preference • Needs the user model to know the user’s goals, knowledge and preferences • Direct guidance can be presented to the user in two ways • If the link is already on the page, it can be outlined or emphasized. Examples WebWatcher and Personal WebWatcher • System can create a dynamic “Next” link which is connected to the next best page

9. Direct Guidance • Direct guidance provides no support for users who do not wish to follow the system’s suggestions • Popular in adaptive educational hypermedia systems

10. Link Ordering (Adaptive Sorting) • Prioritize all the links of a page according to some user valuable criteria from the user model • The closer to the top, the more relevant the link is • The links can be manually reordered by dragging • Manual link reordering is considered by the system as a means of relevance feedback and is used to update the user model.

11. Link Ordering • Cannot be used for contextual links or maps (index page or table of contents) • This technology makes the order of links unstable (it may change each time the user enters the page) • Appropriate where all or some of the pages have an unstable set of links like adaptive news systems

12. Link Hiding • Restricts the navigation space by hiding, removing or disabling links to irrelevant pages • Protects users from the complexity of the whole hyperspace and reduces cognitive overload • Based on the separation of three features of a link, the following variants of link hiding are possible • Link removal-removes the link as well as the anchor • Link hiding- preserves the anchor but removes all visual indications that it is a link • Link disabling-removes the functionality

14. Link Hiding • Used is educational hypermedia systems • Link hiding is a unidirectional technology • Hiding can distinguish between only two states for related pages – relevant or non relevant

15. Link Annotation • Augment links with some visual cues to let the user know more about the page behind the annotated link • Icon based annotations and mouseovers are the most popular techniques • Preserves a stable order with the links • Annotation can distinguish up to six states for related pages

17. Link Generation • Newest adaptive navigation support technology • Creates new, non-authored links on a page • Three kinds of link generation • Discovering new links and adding them permanently to the set of existing links • Generating links for similarity based navigation between items • Dynamic recommendation of links that are useful within the current context to the current user

19. Link Generation vs. Web Recommender • Recommender systems suggest a list of items that are relevant to the user’s short or long terms needs • Navigation systems focus on helping users to find their way through hyperspace by adapting links on a page

20. Comparison of the technologies

21. Adaptation Mechanisms for Adaptive Navigation Support • Simple Adaptation Mechanisms • Content-Based Mechanisms • Social Mechanisms • Indexing-Based Mechanisms

22. Simple Adaptation Mechanisms • Do not require advanced adaptation algorithms • History-Based Mechanisms • Count how many times each node in the hyperspace has been visited and attempt to represent this information visually • Trigger-Based Mechanisms • State of a link is connected with an event • Once the event happens, the link appearance changes • Used by learning management systems • Progress-Based Mechanisms • Tracks the user visit to a page on a deeper level like time spent reading a page or amount of page exploration

24. Content-Based Mechanisms • Make a decision whether to suggest the user a path to a specific page by analyzing page content • If the links is followed, the user profile is updated accordingly

25. Syskill & Webert

26. ScentTrails

27. Social Mechanisms • Based on the idea of social navigation • Offered in two forms • Direct-direct interaction of users with each other in information space • For direct social navigation, annotate links to pages that are currently visited by other users with special icons • Indirect-traces the activities of the community of users • History enriched environments – footprint based approach • Collaborative filtering systems

28. CourseAgent system

29. Indexing-Based Mechanisms • Use manually-produced concept-level document representation and concept-overlay models • Content of each page is expressed in terms of external concept level models • The same external model is used for building an overlay user model and page indexing • The external model used is generally a concept level domain model

30. Classification of Indexing Approaches • Cardinality • Single-concept indexing- each page is related to only one external model concept • Multi-concept indexing-each page can be related to many concepts • Navigation-is the link between concept and a page on a conceptual level or does it define a navigational path? • Expressive Power-amount of information associated with every link between a concept and a page • Role • Weight

31. Basic Approaches to Indexing • Concept Based Hyperspace-used in systems that use single concept indexing • Simple concept based hyperspace • Used in systems that have exactly one page in every system • Hyperspace is the exact replica of the external model • Each concept of external model is represented exactly by one node of the hyperspace • Enhanced concept based hyperspace • Each concept has a corresponding hub page in the hyperspace • Used in adaptive e-learning systems • Page Indexing • Used in systems that use multi concept indexing • Each hypermedia page is indexed with several external model concepts • Concept based Navigation • Combination of the above two approaches

32. Adaptive Navigation Support for Virtual Environments • Text based virtual environments • MUDs • MOOs • Web Virtual Reality