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Adaptive Hypermedia 2ID20 12 Adaptive Hypermedia 2ID20 Prof. dr. Paul De Bra /Department of Computer Science 12 Course Topics • What is adaptive hypermedia? • Reference architecture • Example systems and applications • Evaluation of adaptive hypermedia • The AHA! system • Creating adaptive applications using AHA! /Department of Computer Science 1 12 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) /Department of Computer Science 12 Adaptive Hypermedia Systems Data about user Collects User Modeling Processes System Processes User Model Adaptation Adaptation effect /Department of Computer Science 2 12 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 /Department of Computer Science 12 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. /Department of Computer Science 3 12 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 /Department of Computer Science 12 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 user’s goal(s) in order to adapt (goal can be a topic, a product, an airline trip…) – the system also needs to adapt to the user’s 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 don’t know a close airport to the destination of their trip) /Department of Computer Science 4 12 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 /Department of Computer Science 12 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 /Department of Computer Science 5 12 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! /Department of Computer Science 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 /Department of Computer Science 6 12 Adaptive Presentation /Department of Computer Science 12 Adaptive Navigation Support /Department of Computer Science 7 12 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 /Department of Computer Science 12 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. … /Department of Computer Science 8 12 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) /Department of Computer Science 12 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 /Department of Computer Science 9 12 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: hiding+disabling means the link anchor text is just plain text /Department of Computer Science 12 Example from Interbook 4 3 2 v 1 1. Concept role 3. Current section state 2. Current concept state 4. Linked sections state /Department of Computer Science 10 12 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 /Department of Computer Science 12 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 /Department of Computer Science 11 12 What can we adapt to? (cont.) • Background and experience – background = user’s experience outside the application – experience = user’s experience with the application’s 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 user’s environment, like browsing device, window size, network bandwidth, processing power, etc. /Department of Computer Science 12 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 /Department of Computer Science 12.
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