The Model

We live in a world where the quantity of available information and its rate of growth are rapidly becoming limiting factors as important as the lack of information has been for thousands of years. The Internet and the World Wide Web are the main enabling technologies for this shift. In the past few years, the global distribution of information through Internet has made an enormous mass of information available to any web-connected location in the world. The physical location of information (large libraries, museums, etc.), one of the largest limiting factors in information availability, is now immaterial. With recent advances in wireless communications, all the information is also available on-the-move. At the same time, the conversion of existing information (books, images, etc.) to digital format and the creation of new information in the appropriate format, has proved less overwhelming than it appeared in the early 1990’s. Social networking and collaborative work and the distributed gathering/conversion of information has caused the quantity of electronically available information to grow at an extremely fast rate. This situation has resulted in a dramatic information overload. After a decade of using traditional access paradigms, such as queries on structured database systems and information retrieval or search engines, the feeling that “search does not work” and “information is too hard to find” is now reaching a consensus level. Two different information access modes can be identified: focalized search vs. exploratory search. In focalized search, the user attempts to quickly locate relevant information items on the basis of their contents. In exploratory search (also called browsing) the user explores relationships among items in a database. For example, consider a student using an electronic encyclopedia to produce a term paper on Michelangelo [236]. He quickly locates the section on Michelangelo (among several thousand other sections). This is focalized search. At that point, he explores relationships between Michelangelo and other painters, sculptors, architects, the Italian Renaissance at large, and the political situation in Italy during that period, etc. This is exploratory search. Traditionally, research focused on focalized search. Examples include queries on structured databases and information retrieval (IR) techniques [311], recently