1212 /k October 5, 2000capaciteitsgroepscolloquium1 Adaptive Systems Paul De Bra

1212 /k October 5, 2000capaciteitsgroepscolloquium2 Topics Motivation Examples Adaptation methods Reference model Current research problems Conclusions

1212 /k October 5, 2000capaciteitsgroepscolloquium3 Motivation Old paradigm: –users adapt to the systems they use; –they accept non-intuitive user-interfaces; –they accept interfaces that never learn. New paradigm: –users expect configurable systems; –users expect systems to improve over time.

1212 /k October 5, 2000capaciteitsgroepscolloquium4 Examples Indicators for battery status –(electric shaver, laptop computer, cellphone). TV / VCR –suggests / records your favorite programs –mutes when the phone rings, etc. Car –seat position, radio volume, climate control.

1212 /k October 5, 2000capaciteitsgroepscolloquium5 Examples (cont.) Electronic Program Guide –only provides info on available TV channels; –recommends programs you like (and omits programs you don’t like); –shows the kind of information you want (story, actors, director, text, photograph or video); –adapts presentation to your device (computer with large screen, palmtop, WAP phone).

1212 /k October 5, 2000capaciteitsgroepscolloquium6 Examples (cont.) Real-estate database –shows property in the area of interest; –learns which property you are likely to look into (based on price, kind, neighborhood...); –knows which property you saw before; –shows only those attributes you want to see; –adapts presentation to your device / network.

1212 /k October 5, 2000capaciteitsgroepscolloquium7 Types of Adaptive Systems Embedded Systems: –User-Interface (placement of controls changes); –Dialog (steps are inserted/deleted/reordered). Information Systems: –Query adaptation (select wanted items); –Presentation adaptation (attribute selection and layout).

1212 /k October 5, 2000capaciteitsgroepscolloquium8 Adaptive Hypermedia What’s wrong with “plain” hypermedia? A B

1212 /k October 5, 2000capaciteitsgroepscolloquium9 Adaptive Hypermedia (cont.) How does adaptive hypermedia help? –Provide additional explanations ; –Provide prerequisite explanations for users who have a knowledge deficiency. –Provide comparitive explanations. –Provide explanation variants. –Sorting: present most wanted items first.

1212 /k October 5, 2000capaciteitsgroepscolloquium10 Adaptive Hypermedia (cont.) How does adaptive hypermedia help? –Global guidance: suggest navigation paths; –Local guidance: suggest a page (or small set of pages) to be read next; –Global orientation support: fish-eye view –Local orientation support: show where the user can go next.

1212 /k October 5, 2000capaciteitsgroepscolloquium11 Adaptive Hypermedia (cont.) Is creating adaptive hypermedia more work? –Creating a sloppy website takes little effort; (but users get lost, don’t understand things, etc.) –Creating an excellent static website with the right information and structure for everyone requires a lot of effort (and it still fails); –Creating an adaptive site is somewhere in between...

1212 /k October 5, 2000capaciteitsgroepscolloquium12 Adaptive Hypermedia Architecture Model Domain model: describes content and structure of the information; User model: describes how the user relates to the application; Adaptation model: describes how the information is presented to each user;

1212 /k October 5, 2000capaciteitsgroepscolloquium13 AHAM: Domain Model Atomic units of information: fragments; Fragments are combined into pages; a page constructor describes how a page is built from conditionally included fragments; A set of pages corresponds to a concept; a set of concepts may represent a higher level composite concept.

1212 /k October 5, 2000capaciteitsgroepscolloquium14 AHAM: Domain Model Concepts (and pages) are connected through concept relationships; Links are a common type; a link to a composite concept must be resolved to a destination page through a page selector; Other relationship types can be defined, e.g. prerequisites, inhibitors, etc.

1212 /k October 5, 2000capaciteitsgroepscolloquium15 AHAM: User Model There is a model for each user; (we do not consider group models) For each concept there are a (possibly different) set of attribute/value pairs; –knowledge: how well does the user know this? –read: has the user read something about this? –ready-to-read: may the user read about this?

1212 /k October 5, 2000capaciteitsgroepscolloquium16 AHAM: Adaptation Model Rules that “work” like database triggers: on event(e.g. user accesses a page) if condition is true(e.g. page was ready to be read, or “desired”) then execute an action(augment the “knowledge” of this page)

1212 /k October 5, 2000capaciteitsgroepscolloquium17 AHAM: Adaptive Engine How are these rules executed ? –The system searches for an active rule; –It executes one or more active rules in parallel (set semantics or instance semantics); –The system then again searches for an active rule, etc. until no more active rules are available.

1212 /k October 5, 2000capaciteitsgroepscolloquium18 AHAM: Adaptive Engine Termination of rule execution: –Does the rule execution always terminate? e.g. integer monotonic updates with upper bound; –Is termination decidable? e.g. only finite attribute domains; –If decidable, is detecting (non)termination tractable?

1212 /k October 5, 2000capaciteitsgroepscolloquium19 AHAM: Adaptive Engine Confluence of rule execution: –When more than one rule is active, does the final result of the rule execution depend on which rule is executed first? –When executing rules in parallel, can the resulting updates be conflicting? –Does assigning a priority to rules help?

1212 /k October 5, 2000capaciteitsgroepscolloquium20 Termination in general Study the activation or triggering graph: –nodes are rule instances; –edges connect rules when the action of one rule triggers another rule and the condition of that other rule may be satisfied; –when this graph is acyclic termination is guaranteed (but the converse is not true).

1212 /k October 5, 2000capaciteitsgroepscolloquium21 Confluence in general The “result” of an event may depend on the order of execution of triggered rule: –when two rules can be executed, the action of the first rule may make the condition of the second rule become false. –there is some (active database) theory for deciding whether all rule instances commute.

1212 /k October 5, 2000capaciteitsgroepscolloquium22 Applications at the TU/e 2L690: Hypermedia Structures and Systems (adaptive such that printing is not advisable) 2R350: Graphical User-Interfaces (one source for full text and viewgraphs) IShype: Guide for internships and masters thesis work Corporate TU/e website is next!

1212 /k October 5, 2000capaciteitsgroepscolloquium23 Finally Several adaptive hypermedia applications exist today. (Web-based or non-Web- based) Adaptive hypermedia is no longer a niche novelty. (August 2000, AH2000 conference, Trento, Italy. LNCS 1892) Some theoretical and development work is still needed to create general-purpose AHS.