It is well known that a great number of query--document features which significantly improve the quality of ranking for popular queries, however, do not provide any benefit for new or rare queries since there is typically not enough data associated with those queries that is required to reliably compute the values of those features. It is a common practice to propagate the values of such features from popular to tail queries, if the queries are similar according to some predefined query similarity functions. In this paper, we propose new algorithms that facilitate and increase the effectiveness of this propagation. Given a query similarity function and a query--document relevance feature, we introduce two different approaches (linear weighting approach and tree-based approach) to learn a function of values of the similarity function and values of the feature for the similar queries w.r.t. the given document. The propagated value of the feature equals the value of the obtained function for the given query--document pair.

Graph-based ranking plays a key role in many applications, such as web search and social computing. Pioneering methods of ranking on graphs (e.g., PageRank and HITS) computed ranking scores relying only on the graph structure. Recently proposed methods, such as Semi-Supervised Page-Rank, take into account both the graph structure and the metadata associated with nodes and edges in a unified optimization framework. Such approaches are based on initializing the underlying random walk models with prior weights of nodes and edges that in turn depend on their individual properties. While in those models the prior weights of nodes and edges depend only on their own features, one can also assume that such weights may also depend or be related to the prior weights of their neighbors. This paper addresses the problem of weighting nodes and edges according to this intuition by realizing it in a general ranking model and an efficient algorithm of tuning the parameters of that model.

In the last years, a lot of attention was attracted by the problem of page authority computation based on user browsing behavior. However, the proposed methods have a number of limitations. In particular, they run on a single snapshot of a user browsing graph ignoring substantially dynamic nature of user browsing activity, which makes such methods recency unaware. This paper proposes a new method for computing page importance, referred to as Fresh BrowseRank. The score of a page by our algorithm equals to the weight in a stationary distribution of a flexible random walk, which is controlled by recency-sensitive weights of vertices and edges. Our method generalizes some previous approaches, provides better capability for capturing the dynamics of the Web and users behavior, and overcomes essential limitations of BrowseRank. The experimental results demonstrate that our method enables to achieve more relevant and fresh ranking results than the classic BrowseRank.

Traditional link-based web ranking algorithms run on a single web snapshot without concern of the dynamics of web pages and links. In particular, the correlation of web pages freshness and their classic PageRank is negative (see [11]). For this reason, in recent years a number of authors introduce some algorithms of PageRank actualization. We introduce our new algorithm called Actual PageRank, which generalizes some previous approaches and therefore provides better capability for capturing the dynamics of the Web. To the best of our knowledge we are the first to conduct ranking evaluations of a fresh-aware variation of PageRank on a large data set. The results demonstrate that our method achieves more relevant and fresh results than both classic PageRank and its "fresh" modifications.

We consider the Buckley-Osthus implementation of preferential attachment and its ability to model the web host graph in two aspects. One is the degree distribution that we observe to follow the power law, as often being the case for real-world graphs. Another one is the two-dimensional edge distribution, the number of edges between vertices of given degrees. We fit a single "initial attractiveness" parameter a of the model, first with respect to the degree distribution of the web host graph, and then, absolutely independently, with respect to the edge distribution. Surprisingly, the values of a we obtain turn out to be nearly the same. Therefore the same model with the same value of the parameter a fits very well the two independent and basic aspects of the web host graph. In addition, we demonstrate that other models completely lack the asymptotic behavior of the edge distribution of the web host graph, even when accurately capturing the degree distribution.