Motivation and Goals
There is no doubt that the Internet and its most-popular service World Wide Web have changed our everyday lives. Especially the Web has become an ubiquitous source of information, a communication tool, shopping mall and much more. Along with its size and importance rises a requirement to use it more effectively.
If we want to be able to provide a user with a personalized experience within our web site, we need to base our personalization on some type of user profile, an instance of a user model representing user characteristics and context. The research within the area of user modeling is very well established: the first user modeling workshop took place in Germany in 1986 and evolved into a series of highly credited annual international conferences focused mainly on user modeling for adaptive web-based systems. Despite the old tradition, the research area is still active, with many open challenges, which arise along with development of the Web itself.
Recently, the Web as well as its research got fascinated by a social phe- nomenon. Not only that people are more present on the Web, as they got the tools such as wikis, blogs, social tagging systems or social applications, which allow them to actively participate on the creation of web content, but we discovered the power of masses, wisdom of crowds, which can be used to organize the web content and to provide personalized recommendations using social relationships and group membership. The key are communities, either having real-life back-end or pure virtual ad-hoc communities of people sharing a common property at the given time. While usage driven adapta- tion, mainly in form or statistics-based recommendations is becoming very popular way of navigation, especially in news portals (e.g., simple recom- mendation of the most visited content within a time window), other forms of social recommendations, which would take into account various aspects of a personalized user community are still rather seldom. The challenge is how to represent, build and use a user model for a dynamically changing, often user-generated content.
In our work, we present a contribution in the field of user modeling for adaptive web-based systems, focusing on a shift from static, closed-corpus application domain into dynamic, vast and thus open-corpus application domains such as the Web is. We also target on enrichment of the user model as well as the user modeling process by social-related information.
This can be reduced into two major goals:
In this thesis, we proposed methods which bring novel approaches to user modeling process. We focused on an open corpus user modeling, an approach which handles vast and dynamic information spaces such as the web is. Our main goals were to alleviate incorporation of the user modeling process into legacy web-based systems by extending a standard presentation layer by a user modeling sub-layer. Next, we were looking for solutions, which would bring the personalized experience to the ordinary everyday browsing on the Web by ubiquitous user and community modeling.
More specifically, we proposed and evaluated
The proposed methods represent a contribution in all parts of the user modeling process. Logging of user activity with preserved semantics combined with rule-based user model inference allows for straightforward transformation of user’s clickstream within the web-based system into a set of user model updates. This chaining of methods can be used effectively for both user model maintenance and initialization, to reduce cold-start problem.
We believe that social-based personalization, where we rely more on behavior of visitor and less on complete understanding of the content is the key to finally deliver ubiquitous personalized experience to every website. However, we need to “understand” the content to the extent that allows us to cluster visitors accessing the content into virtual communities so that they can mutually benefit from their community wisdom. This is exactly what we were aiming at by proposing the methods grouped around term-based user modeling, plugged in our specialized proxy server. They contribute to ubiquitous user modeling and open up various possibilities for community-based personalization.
The importance of new methods for open corpus personalization is even more visible, if we realize that traditional closed corpus web-based systems are being replaced by the systems driven by Web 2.0 principles. The most important one from our point of view is the support for user-generated content, which eliminates the difference between the roles of a Web producer and a Web consumer. Majority of web-based systems are thus becoming open-corpus and cannot directly apply traditional methods and techniques for closed corpus user modeling.