Private Information Retrieval (PIR) schemes allow a user to retrieve the i-th bit of an n-bit database x, replicated in k servers, while keeping the value of i private from each server. A t-private PIR scheme protects the user's privacy from any collusion of up to t servers. The main cost measure for such schemes is their communication complexity. We introduce a new technique for the constructi...

The traditional information retrieval technologies are based on keywords, and therefore provide limited capabilities to capture the conceptualizations associated with user needs and contents. As a new technology of information retrieval, semantic retrieval can retrieve information resource fully and precisely based on the knowledge understanding and knowledge reasoning. Ontology, which can well...

The paper introduces an approach to privacy enhancing technologies that sees privacy not merely as an individual right, but as a public good. This understanding of privacy has recently gained ground in the debate on appropriate legal protection for privacy in an online environment. The jurisprudential idea that privacy is a public good and prerequisite for a functioning democracy also entails t...

In this paper we present and analyze a general scheme for one database computationally Private Information Retrieval. This scheme was first presented by Ostrovsky and Skeith in [13]. This general framework shows such a PIR scheme based on any secure homomorphic public key encryption scheme. We complete the analysis of this framework, present a proof of security, and do a careful analysis of the...

We(Tsinghua University) participated both Ad Hoc Retrieval Task and Categorization Task in TREC2005 Genomics Track, in which we designed and implemented a serious of methods encompassed learning domain-specific knowledge from context. In Ad Hoc Retrieval Task, internal resource is introduced to expand query, different granularity indexing provides more flexible retrieval space, and pattern disc...

This article focuses on the field of Semantic Information Retrieval (IR), which is at the intersection of several disciplines: Information Retrieval, Knowledge Engineering and Natural Language Processing. We present the basics to understand how a semantic IR system works. We also present a classification of the types of semantic resources used in information retrieval. We detail the role of the...

We present a gold standard for the evaluation of Cross Language Information Retrieval systems in the domain of Organic Agriculture and AgroEcology. The presented resource is free to use for research purposes and it includes a collection of multilingual documents annotated with respect to a domain ontology, the ontology used for annotating the resources, a set of 48 queries in 12 languages and a...

The advent of Web 2.0 has created a proliferation of resource sharing sites where individual users tag resources. Retrieval performance is good when users share the same vocabulary, but deteriorates when users have diverging vocabularies. In this paper we propose a novel method of reusing search experience to transform the underlying representation of tagged resources. The aim is to favour thos...