Adaptive Hypermedia 2ID20

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Adaptive Hypermedia2ID20

• Prof. dr. Paul De Bra

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Course Topics

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

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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)

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Adaptive Hypermedia Systems
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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

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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.

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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

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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)

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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

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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

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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!

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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

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Adaptive Presentation
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Adaptive Navigation Support
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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

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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.

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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)

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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

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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

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Example from Interbook
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2
v
1
1. Concept role 2. Current concept state
3. Current section state 4. Linked sections state
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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

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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

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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.

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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