Research Project

Nearest-Neighbor Searching Under Uncertainty

Speaker:Wuzhou Zhang
wuzhou at
Date: Thursday, March 22, 2012
Time: 1:00pm - 2:30pm
Location: D344 LSRC, Duke
Kamesh Munagala, Jun Yang


Nearest-neighbor queries, which ask for returning the nearest neighbor of a query point in a set of points, are important and widely studied in many fields because of a wide range of applications. In many of these applications, such as sensor databases, location based services, face recognition, and mobile data, the location of data is imprecise. We therefore study nearest neighbor queries in a probabilistic framework in which the location of each input point and/or query point is specified as a probability density function and the goal is to return the point that minimizes the expected distance, which we refer to as the expected nearest neighbor (ENN). We present methods for computing an exact ENN or an eps-approximate ENN, for a given error parameter eps > 0, under different distance functions. These methods build an index of near-linear size and answer ENN queries in polylogarithmic or sublinear time, depending on the underlying function. As far as we know, these are the first nontrivial methods for answering exact or eps-approximate ENN queries with provable performance guarantees. Joint work with Pankaj K. Agarwal, Alon Efrat, and Swaminathan Sankararaman. To appear in PODS 2012.
Advisor(s): Pankaj Agarwal