With the rapid development of Web 2.0, more and more people are sharing their opinions about online products, so there is much product review data. However, it is difficult to compare products directly using ratings because many ratings are based on different scales or ratings are even missing. This paper addresses the following question: given textual reviews, how can we automatically determine the semantic orientations of reviewers and then rank different items? Due to the absence of ratings in many reviews, it is difficult to collect sufficient rating data for certain specific categories of products (e.g., movies), but it is easier to find rating data in another different but related category (e.g., books). We refer to this problem as transfer rating, and try to train a better ranking model for items in the interested category with the help of rating data from another related category. Specifically, we developed a ranking-oriented method called TRate for determining the semantic orientations and for ranking different items and formulated it in a regularized algorithm for rating knowledge transfer by bridging the two related categories via a shared latent semantic space. Tests on the Epinion dataset verified its effectiveness.
In this paper, we propose Term-based Semantic Peer-to-Peer Networks (TSPN) to achieve semantic search. For each peer, TSPN builds a full text index of its documents. Through the analysis of resources, TSPN obtains series of terms, and distributes these terms into the network. Thus, TSPN can use query terms to locate appropriate peers to perform semantic search. Moreover, unlike the traditional structured P2P networks, TSPN uses the terms, not the peers, as the logical nodes of DHT. This can with-stand the impact of network churn. The experimental results show that TSPN has better performance compared with the existing P2P semantic searching algorithms.
Quorum system is a preferable model to construct distributed access control architecture, but not all quorum system can satisfy the requirements of distributed access control architecture. Aiming at the dependable problem of authorization server in distributed system and combining the requirements of access control, a set of criterions to select and evaluate quorum system is presented. The scheme and algorithm of constructing an authorization server system based on Paths quorum system are designed, and the integrated system performance under some servers attacked is fully analyzed. Role-based access control on the Web implemented by this scheme is introduced. Analysis shows that with certain node failure probability, the scheme not only has high dependability but also can satisfy the special requirements of distributed access control such as real-time, parallelism, and consistency of security policy.
