Abstract not found

We study the fundamental problem of computing distances between nodes in large graphs such as the web graph and social networks. Our objective is to be able to answer distance queries between pairs of nodes in real time. Since the standard shortest path algorithms are expensive, our approach moves the time-consuming shortest-path computation offline, and at query time only looks up precomputed values and performs simple and fast computations on these precomputed values. More specifically, during the offline phase we compute and store a small “sketch ” for each node in the graph, and at query-time we look up the sketches of the source and destination nodes and perform a simple computation using these two sketches to estimate the distance. Categories and Subject Descriptors G.2.2 [Graph Theory]: Graph algorithms, path and circuit problems

First I would like to thank my advisor, Professor George Kollios for his constant guidance and support. I would also like to thank Vassilis Athitsos and Aris Gionis who have eagerly guided me and worked with me at various times during my graduate studies. A special thank you goes to Professor Stan Sclaroff for his insightful remarks on the content of this thesis. I was also lucky to collaborate with Francesco Bonchi and Carlos Castillo during my participation in the Yahoo! Research Internship program; this work could not have been completed without their contribution. I thank my dearest friends Giorgos, Giorgos, Niky, Panos, Vijay and Yola for putting up with me. I cannot express enough gratitude to my closest friends back home for still being around despite the distance. As always, above all, I am grateful to my family. iv INDEXING DISTANCES IN LARGE GRAPHS AND APPLICATIONS IN SEARCH TASKS MICHALIS POTAMIAS This thesis elaborates on the problem of preprocessing a large graph so that single-pair shortestpath queries can be answered quickly at runtime. Computing shortest paths is a well studied problem,