Expertise-based peer selection in Peer-to-Peer networks

Peer-to-Peer systems have proven to be an effective way of sharing data. Modern protocols are able to efficiently route a message to a given peer. However, determining the destination peer in the first place is not always trivial. We propose a a message to a given peer. However, determining the destination peer in the first place is not always trivial. We propose a model in which peers advertise their expertise in the Peer-to-Peer network. The knowledge about the expertise of other peers forms a semantic topology. Based on the semantic similarity between the subject of a query and the expertise of other peers, a peer can select appropriate peers to forward queries to, instead of broadcasting the query or sending it to a random set of peers. To calculate our semantic similarity measure, we make the simplifying assumption that the peers share the same ontology. We evaluate the model in a bibliographic scenario, where peers share bibliographic descriptions of publications among each other. In simulation experiments complemented with a real-world field experiment, we show how expertise-based peer selection improves the performance of a Peer-to-Peer system with respect to precision, recall and the number of messages

Do we need a Unique Scientist ID for publications in biomedicine?

BACKGROUND: The PubMed database contains nearly 15 million references from more than 4,800 biomedical journals. In general, authors of scientific articles are addressed by their last name and forename initial. DISCUSSION: In general, names can be too common and not unique enough to be search criteria. Today, Ph.D. students, other researchers and women publish scientific work. A person may not only have one name but several names and publish under each name. A Unique Scientist ID could help to address people in peer-to-peer (P2P) networks. As a starting point, perhaps PubMed could generate and manage such a scientist ID. SUMMARY: A Unique Scientist ID would improve knowledge management in science. Unfortunately in some of the publications, and then within the online databases, only one letter abbreviates the author's forename. A common name with only one initial could retrieve pertinent citations, but include many false drops (retrieval matching searched criteria but indisputably irrelevant)

Peer Data Management

Peer Data Management (PDM) deals with the management of structured data in unstructured peer-to-peer (P2P) networks. Each peer can store data locally and define relationships between its data and the data provided by other peers. Queries posed to any of the peers are then answered by also considering the information implied by those mappings. The overall goal of PDM is to provide semantically well-founded integration and exchange of heterogeneous and distributed data sources. Unlike traditional data integration systems, peer data management systems (PDMSs) thereby allow for full autonomy of each member and need no central coordinator. The promise of such systems is to provide flexible data integration and exchange at low setup and maintenance costs. However, building such systems raises many challenges. Beside the obvious scalability problem, choosing an appropriate semantics that can deal with arbitrary, even cyclic topologies, data inconsistencies, or updates while at the same time allowing for tractable reasoning has been an area of active research in the last decade. In this survey we provide an overview of the different approaches suggested in the literature to tackle these problems, focusing on appropriate semantics for query answering and data exchange rather than on implementation specific problems

An intelligent peer-to-peer multi-agent system for collaborative management of bibliographic databases

This paper describes the design of a peer-to-peer system for collaborative management of distributed bibliographical databases. The goal of this system is twofold: firstly, it aims at providing help for users to manage their local bibliographical databases. Secondly, it offers the possibility to exchange bibliographical data among like-minded user groups in an implicit and intelligent manner. Each user is assisted by a personal agent that provides help such as: filling in bibliographical records, verifying the correctness of information entered and more importantly, recommendation of relevant bibliographical references. To do this, the personal agent needs to collaborate with its peers in order to get relevant recommendations. Each agent applies a case-based reasoning approach in order to provide peers with requested recommendations. The paper focuses mainly on describing the recommendation computation approach

Semantic Routing in Peer-to-Peer Systems

Currently search engines like Google, Yahoo and Excite are centralized, which means that all queries that users post are sent to some big servers (or server group) that handle them. In this way it is easy for the systems to relate IP-addresses with the queries posted from them. Clearly privacy is a problem here. Also censoring out certain information which is not 'appropriate' is simple, and shown in recent examples. To give more privacy to the users and make censoring information more difficult, Peer-to-Peer (P2P) systems are a good alternative to the centralized approach. In P2P systems the search functionality can be devided over a large group of autonomous computers (Peers), where each computer only has a very small piece of information instead of everything. Now the problem in such a distributed system is to make the search process efficient in terms of bandwith, storage, time and CPU usage. In this Ph.D. thesis, three approaches are described that try to reach goal of finding the short routes between seeker and providers with high efficiency. These routing algorithms are all applied on 'Semantic-Overlay-Networks' (SONs). In a SON, peers maintain pointers to semantically relevant peers based on content descriptions, which makes them able to choose the relevant peers for queries instead of, for example, choosing random peers. This work tries to show that decentralized search algorithms based on semantic routing are a good alternative to centralized approaches.Harmelen, F.A.H. van [Promotor

Semantic Flooding: Semantic Search across Distributed Lightweight Ontologies

Lightweight ontologies are trees where links between nodes codify the fact that a node lower in the hierarchy describes a topic (and contains documents about this topic) which is more specific than the topic of the node one level above. In turn, multiple lightweight ontologies can be connected by semantic links which represent mappings among them and which can be computed, e.g., by ontology matching. In this paper we describe how these two types of links can be used to define a semantic overlay network which can cover any number of peers and which can be flooded to perform a semantic search on documents, i.e., to perform semantic flooding. We have evaluated our approach by simulating a network of 10,000 peers containing classifications which are fragments of the DMoz web directory. The results are promising and show that, in our approach, only a relatively small number of peers needs to be queried in order to achieve high accuracy

SiFo-Peers: A Social FOAF Based Peer-to-Peer Network

In this paper, an attempt is made to conceptually unite three different application areas for semantic technologies, namely personal Knowledge Management, social networking, and Peer-to-Peer information-sharing. Until now, semantic technology has been applied to each of these application areas separately or in binary combinations only. By functionally combining all three areas in a single application, it is hoped to sketch a compelling Semantic Web system that will help increase the spread and acceptance of the Semantic Web vision. A concrete usage scenario of a community of researchers is used to demonstrate the approach

Lightweight Synchronization of Ontologies

Master's thesis, RWTH, Aachen (DE) - sharma2006aThe semantic web is based on the idea of having formalized knowledge expressed on the web (in languages like RDF). However, we know that people do not like to strictly comply with some ontology and they would tend to add their own tags within existing ontology descriptions. This thesis addresses the issue of heterogeneity within the domain of photo annotation. It presents a peer-to-peer infrastructure and client software that enables users to provide ontology based photo annotations in a free manner (by using the most convenient vocabulary) and share them with other users in a peer-to-peer environment. Moreover, the thesis presents an ontology alignment based mediator service to translate queries among the peers