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Adaptive Hypermedia 2ID20

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Title: Adaptive Hypermedia 2ID20


1
Adaptive Hypermedia2ID20
  • Prof. dr. Paul De Bra


2
Course Topics
  • What is adaptive hypermedia?
  • Reference architecture
  • Example systems and applications
  • Evaluation of adaptive hypermedia
  • The AHA! system
  • Creating adaptive applications using AHA!

3
What is Adaptive Hypermedia?
  • Hypermedia
  • different media types used in a single
    application (text, images, sound, video, )
  • non-linear structure with navigation through
    hyper-links
  • Adaptive
  • application forms a model of the context in which
    it is used (user, place, time, device, etc.)
  • application adapts to that context (can show
    different information, different media, different
    links, etc.)
  • adaptation and user modeling interact with each
    other (or else we say the application is
    adaptable, not adaptive)

4
Adaptive Hypermedia Systems
5
Why Adaptive Hypermedia?
  • Problems with (non-adaptive) hypermedia
  • authoring hypermedia is difficult because of the
    navigational freedom of end-users
  • using hypermedia is difficult because the author
    did not anticipate the path the end-user follows
  • using hypermedia is also difficult because it is
    easy to get lost in hyperspace
  • Solutions through adaptive hypermedia
  • compensate for unexpected comprehension problems
    due to the chosen navigation paths
  • warn users before following links that lead to
    problematic navigation paths
  • offer orientation support using adaptive overviews

6
Application Areas
  • Educational hypermedia systems
  • on-line course text, with on-line multiple-choice
    or other machine-interpretable tests
  • On-line information systems
  • information kiosk, documentation systems,
    encyclopedias, etc.
  • On-line help systems
  • context-sensitive help, (think of Clippy)
  • Information retrieval and filtering
  • adaptive recommender systems
  • etc.

7
Adaptive Educational Hypermedia
  • Origin Intelligent Tutoring Systems
  • combination of reading material and tests
  • adaptive course sequencing, depending on test
    results
  • In Adaptive Educational Hypermedia
  • more freedom for the learner guidance instead of
    enforced sequence
  • adaptive content of the course material to solve
    comprehension problems when pages or chapters are
    read out of sequence
  • adaptation based on reading as well as tests

8
Adaptive On-line Information Systems
  • Examples encyclopedia, documentation, but also
    shopping sites, airline reservation, etc.
  • goal provide information about different topics
  • users are only interested in a few topics, not in
    studying the entire hyperspace
  • the system needs to know the users goal(s) in
    order to adapt (goal can be a topic, a product,
    an airline trip)
  • the system also needs to adapt to the users
    knowledge and background, perhaps also location
    (e.g. departing city)
  • users need help most when the concepts they want
    do not match the concept structure of the
    application (e.g. they dont know a close airport
    to the destination of their trip)

9
Adaptive On-line Help Systems
  • Like on-line information systems, but
  • not independent but tied into an application (and
    called from that application)
  • (part of) the context is known through the
    application
  • often this context is the only information about
    the user needed to adapt the information
  • hyperspace is reasonably small
  • unfortunately adaptation does not turn bad help
    information into good, and it cannot compensate
    for missing help information
  • popular (bad) examples Windows troubleshooter,
    Clippy

10
Adaptive Information Retrieval/Filtering
  • Adaptive Retrieval
  • adaptively refine search requests
  • adaptively filter out non-relevant search results
  • update user model based on implicit or explicit
    relevance feedback
  • context information to be used can be a task,
    perhaps from a workflow system
  • Adaptive Filtering
  • filters incoming information without the user
    explicitly asking for it
  • a personalized view interface for the Web can
    also be viewed as a filter
  • relies on relevance feedback to form and update a
    user model

11
The Future Ambient Intelligence
  • Intelligent home (and office or building)
  • automatic heating/climate control
  • automatic lighting, kitchen,
  • automatic communication redirection
  • adaptive information services and help
  • adaptive technology makes the technology
    disappear into the environment
  • a dream? not for long!

12
What Do We Adapt in AH?
  • Adaptive presentation
  • adapting the information
  • adapting the presentation of that information
  • selecting the media and media-related factors
    such as image or video quality and size
  • Adaptive navigation
  • adapting the link anchors that are shown
  • adapting the link destinations
  • giving overviews for navigation support and for
    orientation support

13
Adaptive Presentation
14
Adaptive Navigation Support
15
Canned Text Adaptation
  • Inserting/removing fragments
  • prerequisite explanations inserted when the user
    appears to need them
  • additional explanations additional details or
    examples for some users
  • comparative explanations only shown to users who
    can make the comparison
  • Altering fragments
  • Most useful for selecting among a number of
    alternatives
  • Can be done to choose explanations or examples,
    but also to choose a single term
  • Sorting fragments
  • Can be done to perform relevance ranking for
    instance

16
Example from 2L690
  • Before reading about Xanadu the URL page shows
  • In Xanadu (a fully distributed hypertext
    system, developed by Ted Nelson at Brown
    University, from 1965 on) there was only one
    protocol, so that part could be missing.
  • After reading about Xanadu this becomes
  • In Xanadu there was only one protocol, so that
    part could be missing.

17
Canned Text Adaptation (cont.)
  • Stretchtext
  • Similar to replacement links in the Guide
    hypertext system
  • Items can be open or closed system decides
    adaptively which items to open when a page is
    accessed
  • Dimming fragments
  • Text not intended for this user is de-emphasized
    (grayed out, smaller font, etc.)
  • Can be combined with stretchtext to create
    de-emphasized text that conditionally appears, or
    only appears after some event (like clicking on a
    tooltip icon)

18
Adaptive Navigation Support
  • Direct guidance
  • like an adaptive guided tour
  • next button with adaptively determined link
    destination
  • Adaptive link generation
  • the system may discover new useful links between
    pages and add them
  • the system may use previous navigation or page
    similarity to add links
  • generating a list of links is typical in
    information retrieval and filtering systems

19
Adaptive Navigation Support (cont.)
  • Adaptive link annotation
  • all links are visible, but an annotation
    indicates relevance
  • the link anchor may be changed (e.g. in color) or
    additional annotation symbols can be used
  • Adaptive link hiding
  • pure hiding means the link anchor is shown as
    normal text (the user cannot see there is a link)
  • link disabling means the link does not work it
    may or may not still be shown as if it were a
    link
  • link removal means the link anchor is removed
    (and as a consequence the link cannot be used)
  • a combination is possible hidingdisabling means
    the link anchor text is just plain text

20
Example from Interbook
4

3
2
v
1
1. Concept role 2. Current concept state
3. Current section state 4. Linked sections state
21
Adaptive Navigation Support (cont.)
  • Map adaptation
  • complete (site)maps are not feasible for a
    non-trivial hyperspace
  • a local or global map can be adapted by
    annotating or removing nodes or larger parts
  • a map can also be adapted by moving nodes around
  • maps can be graphical or textual
  • adaptation can be based on relevance, but also on
    group presence

22
What can we adapt to?
  • Knowledge of the user
  • initialization using stereotypes (beginner,
    intermediate, expert)
  • represented in an overlay model of the concept
    structure of the application
  • fine grained or coarse grained
  • based on browsing and on tests
  • Goals, tasks or interest
  • mapped onto the applications concept structure
  • difficult to determine unless it is preset by the
    user or a workflow system
  • goals may change often and more radically than
    knowledge

23
What can we adapt to? (cont.)
  • Background and experience
  • background users experience outside the
    application
  • experience users experience with the
    applications hyperspace
  • Preferences
  • any explicitly entered aspect of the user that
    can be used for adaptation
  • examples media preferences, cognitive style,
    etc.
  • Context / environment
  • aspects of the users environment, like browsing
    device, window size, network bandwidth,
    processing power, etc.

24
Web-based Adaptive Hypermedia
  • Client-server architecture using HTTP
  • only page accesses are registered (not scrolling,
    within-page scripting code or animations, etc.)
  • following a link activates a server-side program
    (CGI-script, Java Servlet, )
  • the program uses the link URL and the user model
    to determine which page to return
  • the program performs content and link adaptation
    based on the user model (and some adaptation
    rules)
  • the program updates the user model taking into
    account that the user will read the presented
    information
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