Ronny Lempel
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Publications by Ronny Lempel (bibliography)
» 2007 «
Lempel, Ronny, Mass, Yosi, Ofek-Koifman, Shila, Sheinwald, Dafna, Petruschka, Yael and Sivan, Ron (2007): Just in time indexing for up to the second search. In: Silva, Mario J., Laender, Alberto H. F., Baeza-Yates, Ricardo A., McGuinness, Deborah L., Olstad, Bjørn, Olsen, Øystein Haug and Falcão, André O. (eds.) Proceedings of the Sixteenth ACM Conference on Information and Knowledge Management - CIKM 2007 November 6-10, 2007, Lisbon, Portugal. pp. 97-106. Available online
» 2004 «
Amitay, Einat, Carmel, David, Lempel, Ronny and Soffer, Aya (2004): Scaling IR-system evaluation using term relevance sets. In: Proceedings of the 27th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval 2004. pp. 10-17. Available online
“This paper describes an evaluation method based on Term Relevance Sets Trels that measures an IR system's quality by examining the content of the retrieved results rather than by looking for pre-specified relevant pages. Trels consist of a list of terms believed to be relevant for a particular query as well as a list of irrelevant terms. The proposed method does not involve any document relevance judgments, and as such is not adversely affected by changes to the underlying collection. Therefore, it can better scale to very large, dynamic collections such as the Web. Moreover, this method can evaluate a system's effectiveness on an updatable "live" collection, or on collections derived from different data sources. Our experiments show that the proposed method is very highly correlated with official TREC measures.”
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Amitay, Einat, Carmel, David, Herscovici, Michael, Lempel, Ronny and Soffer, Aya (2004): Trend detection through temporal link analysis. In JASIST - Journal of the American Society for Information Science and Technology, 55 (14) pp. 1270-1281
Broder, Andrei Z., Lempel, Ronny, Maghoul, Farzin and Pedersen, Jan (2004): Efficient PageRank approximation via graph aggregation. In: Proceedings of the 2004 International Conference on the World Wide Web 2004. pp. 484-485. Available online
“We present a framework for approximating random-walk based probability distributions over Web pages using graph aggregation. We (1) partition the Web's graph into classes of quasi-equivalent vertices, (2) project the page-based random walk to be approximated onto those classes, and (3) compute the stationary probability distribution of the resulting class-based random walk. From this distribution we can quickly reconstruct a distribution on pages. In particular, our framework can approximate the well-known PageRank distribution by setting the classes according to the set of pages on each Web host. We experimented on a Web-graph containing over 1.4 billion pages, and were able to produce a ranking that has Spearman rank-order correlation of 0.95 with respect to PageRank. A simplistic implementation of our method required less than half the running time of a highly optimized implementation of PageRank, implying that larger speedup factors are probably possible.”
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Lempel, Ronny and Moran, Shlomo (2004): Optimizing result prefetching in web search engines with segmented indices. In ACM Trans. Internet Techn., 4 (1) pp. 31-59
» 2003 «
Amitay, Einat, Carmel, David, Darlow, Adam, Lempel, Ronny and Soffer, Aya (2003): The connectivity sonar: detecting site functionality by structural patterns. In: Proceedings of the Fourteenth ACM Conference on Hypertext 2003. pp. 38-47. Available online
“Web sites today serve many different functions, such as corporate sites, search engines, e-stores, and so forth. As sites are created for different purposes, their structure and connectivity characteristics vary. However, this research argues that sites of similar role exhibit similar structural patterns, as the functionality of a site naturally induces a typical hyperlinked structure and typical connectivity patterns to and from the rest of the Web. Thus, the functionality of Web sites is reflected in a set of structural and connectivity-based features that form a typical signature. In this paper, we automatically categorize sites into eight distinct functional classes, and highlight several search-engine related applications that could make immediate use of such technology. We purposely limit our categorization algorithms by tapping connectivity and structural data alone, making no use of any content analysis whatsoever. When applying two classification algorithms to a set of 202 sites of the eight defined functional categories, the algorithms correctly classified between 54.5% and 59% of the sites. On some categories, the”
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Lempel, Ronny and Moran, Shlomo (2003): Predictive caching and prefetching of query results in search engines. In: Proceedings of the 2003 International Conference on the World Wide Web 2003. pp. 19-28. Available online
“We study the caching of query result pages in Web search engines. Popular search engines receive millions of queries per day, and efficient policies for caching query results may enable them to lower their response time and reduce their hardware requirements. We present PDC (probability driven cache), a novel scheme tailored for caching search results, that is based on a probabilistic model of search engine users. We then use a trace of over seven million queries submitted to the search engine AltaVista to evaluate PDC, as well as traditional LRU and SLRU based caching schemes. The trace driven simulations show that PDC outperforms the other policies. We also examine the prefetching of search results, and demonstrate that prefetching can increase cache hit ratios by 50% for large caches, and can double the hit ratios of small caches. When integrating prefetching into PDC, we attain hit ratios of over 0.53.”
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» 2002 «
Lempel, Ronny and Soffer, Aya (2002): PicASHOW: pictorial authority search by hyperlinks on the web. In ACM Transactions on Information Systems, 20 (1) pp. 1-24
“We describe PicASHOW, a fully automated WWW image retrieval system that is based on several link-structure analyzing algorithms. Our basic premise is that a page p displays (or links to) an image when the author of p considers the image to be of value to the viewers of the page. We thus extend some well known link-based WWW page retrieval schemes to the context of image retrieval.PicASHOW's analysis of the link structure enables it to retrieve relevant images even when those are stored in files with meaningless names. The same analysis also allows it to identify image containers and image hubs. We define these as Web pages that are rich in relevant images, or from which many images are readily accessible.PicASHOW requires no image analysis whatsoever and no creation of taxonomies for preclassification of the Web's images. It can be implemented by standard WWW search engines with reasonable overhead, in terms of both computations and storage, and with no change to user query formats. It can thus be used to easily add image retrieving capabilities to standard search engines.Our results demonstrate that PicASHOW, while relying almost exclusively on link analysis, compares well with dedicated WWW image retrieval systems. We conclude that link analysis, a proven effective technique for Web page search, can improve the performance of Web image retrieval, as well as extend its definition to include the retrieval of image hubs and containers.”
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Aridor, Yariv, Carmel, David, Maarek, Yoelle S., Soffer, Aya and Lempel, Ronny (2002): Knowledge encapsulation for focused search from pervasive devices. In ACM Transactions on Information Systems, 20 (1) pp. 25-46
“Mobile knowledge seekers often need access to information on the Web during a meeting or on the road, while away from their desktop. A common practice today is to use pervasive devices such as Personal Digital Assistants or mobile phones. However, these devices have inherent constraints (e.g., slow communication, form factor) which often make information discovery tasks impractical.In this paper, we present a new focused-search approach specifically oriented for the mode of work and the constraints dictated by pervasive devices. It combines focused search within specific topics with encapsulation of topic-specific information in a persistent repository. One key characteristic of these persistent repositories is that their footprint is small enough to fit on local devices, and yet they are rich enough to support many information discovery tasks in disconnected mode. More specifically, we suggest a representation for topic-specific information based on "knowledge-agent bases" that comprise all the information necessary to access information about a topic (under the form of key concepts and key Web pages) and assist in the full search process from query formulation assistance to result scanning on the device itself. The key contribution of our work is the coupling of focused search with encapsulated knowledge representation making information discovery from pervasive devices practical as well as efficient. We describe our model in detail and demonstrate its aspects through sample scenarios.”
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» 2001 «
Lempel, Ronny and Moran, Simone (2001): SALSA: the stochastic approach for link-structure analysis. In ACM Transactions on Information Systems, 19 (2) pp. 131-160
“Today, when searching for information on the WWW, one usually performs a query through a term-based search engine. These engines return, as the query's result, a list of Web pages whose contents matches the query. For broad-topic queries, such searches often result in a huge set of retrieved documents, many of which are irrelevant to the user. However, much information is contained in the link-structure of the WWW. Information such as which pages are linked to others can be used to augment search algorithms. In this context, Jon Kleinberg introduced the notion of two distinct types of Web pages: hubs and authorities. Kleinberg argued that hubs and authorities exhibit a mutually reinforcing relationship: a good hub will point to many authorities, and a good authority will be pointed at by many hubs. In light of this, he devised an algorithm aimed at finding authoritative pages. We present SALSA, a new stochastic approach for link-structure analysis, which examines random walks on graphs derived from the link-structure. We show that both SALSA and Kleinberg's Mutual Reinforcement approach employ the same meta-algorithm. We then prove that SALSA is equivalent to a weighted in degree analysis of the link-structure of WWW subgraphs, making it computationally more efficient than the Mutual reinforcement approach. We compare that results of applying SALSA to the results derived through Kleinberg's approach. These comparisons reveal a topological Phenomenon called the TKC effect which, in certain cases, prevents the Mutual reinforcement approach from identifying meaningful authorities.”
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Lempel, Ronny and Soffer, Aya (2001): PicASHOW: pictorial authority search by hyperlinks on the Web. In: Proceedings of the 2001 International Conference on the World Wide Web 2001. pp. 438-448. Available online
Aridor, Yariv, Carmel, David, Maarek, Yoelle S., Soffer, Aya and Lempel, Ronny (2001): Knowledge encapsulation for focused search from pervasive devices. In: Proceedings of the 2001 International Conference on the World Wide Web 2001. pp. 754-764. Available online
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Mar 19th, 2010
Changes to this page (author)
15 Feb 2010: Enabled abstracts to be shown on Ronny Lempel's author page.18 Aug 2009: Author was edited 09 Jul 2009: Author was edited
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28 Apr 2003: Added the author to the bibliography
