Navigability of Decentralized Information Networks

In the early days of Hypertext and the World Wide Web, navigational support for information structures has mostly been designed by small numbers of hypertext engineers, taxonomists or system engineers. The information structures that make up the fabric of today`s World Wide Web however are usually the result of the interactions between a large number of users who dynamically construct these structures through some strong or weak forms of collaboration. As a result, the topological structure and navigability of decentralized information structures such as Wikis, social tagging systems or recommendation systems today is usually unknown, navigational support for users is rudimentary at best, and tools and techniques for shaping navigability are mostly missing. While search has made significant progress over the last two decades, navigability of such systems is a pressing practical and an open research problem. The overall vision of this project is to study factors that shape the navigability of decentralized information networks and to equip their user interfaces with automatic and effective navigational aids that augment users in exploratory tasks. The objectives of this project are the following: (i) To study factors that shape navigability, we will model navigational behavior of users in decentralized information networks by adapting cognitive and network-theoretic theories such as information foraging, decentralized search and others. (ii) To simulate navigation, we will build on and expand a rudimentary network-theoretic simulation framework developed by our group that has been proven useful in preliminary studies. (iii) To verify and validate this framework, we will do simulations and perform human subject studies that will reveal useful parameters and contribute to theory development (through e.g. click-data studies). (iv) To devise automatic and effective navigational aids for large decentralized information networks, we will run simulation experiments of different navigation paradigms and approaches (such as hierarchies, facets, breadcrumbs, recommenders, etc) that will reveal their effectiveness from a network-theoretic perspective. (v) To validate practical effectiveness of these navigational aids, we will integrate these aids into user interfaces of real-world decentralized information networks and do studies of a range of navigational tasks involving human subjects. The results of this project will increase our understanding about the conditions under which navigability emerges in information networks, and about the ways in which navigability of information networks can be shaped through automated interventions.

The goal of this project was to study navigability of large decentralized Web-based information networks such as Wikipedia or recommender systems. In other words, we were interested in detecting how difficult is to find relevant information by browsing and navigating such systems. The navigability of information networks is a complex property that depends on many factors such as the connectivity of the network, the existence of shortcuts which connect thematically distant parts of the network, the strategies that users adopt when navigating the networks, as well as design decisions that system operators make in their systems. In our project we were firstly able to gain new insights in how users navigate on the Web. This enabled us to develop a unified approach for formalizing various aspects of this behaviour in the form of mathematical constructs such as transition matrices. This, in turn allowed us to study the interplay between user navigational behaviour and the structure of the information networks that they navigate. With this approach we are able to, for example, indentify potential problems in information networks which could lead to poor support of users when they browse a given system. Moreover, with our approach we can analyze the consequences of possible modifications that system operators may adopt to remedy the problems in their systems. The application of the methods developed in this project aim at the discovery of ways how to better support humans in their navigation on the Web by automatic modification of the underlying networks.