An Zhu

An Zhu

An Zhu is currently a Staff Software Engineer at Google. Her home page is at: http://www.cs.stanford.edu/~anzhu.
Authored Publications
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    Achieving anonymity via clustering
    Tomás Feder
    Krishnaram Kenthapadi
    Samir Khuller
    Rina Panigrahy
    Dilys Thomas
    ACM Transactions on Algorithms, 6 (2010), 49:1-49:19
    Preview abstract Publishing data for analysis from a table containing personal records, while maintaining individual privacy, is a problem of increasing importance today. The traditional approach of de-identifying records is to remove identifying fields such as social security number, name etc. However, recent research has shown that a large fraction of the US population can be identified using non-key attributes (called quasi-identifiers) such as date of birth, gender, and zip code. Sweeney proposed the k-anonymity model for privacy where non-key attributes that leak information are suppressed or generalized so that, for every record in the modified table, there are at least k−1 other records having exactly the same values for quasi-identifiers. We propose a new method for anonymizing data records, where quasi-identifiers of data records are first clustered and then cluster centers are published. To ensure privacy of the data records, we impose the constraint that each cluster must contain no fewer than a pre-specified number of data records. This technique is more general since we have a much larger choice for cluster centers than k-Anonymity. In many cases, it lets us release a lot more information without compromising privacy. We also provide constant-factor approximation algorithms to come up with such a clustering. This is the first set of algorithms for the anonymization problem where the performance is independent of the anonymity parameter k. We further observe that a few outlier points can significantly increase the cost of anonymization. Hence, we extend our algorithms to allow an epsilon fraction of points to remain unclustered, i.e., deleted from the anonymized publication. Thus, by not releasing a small fraction of the database records, we can ensure that the data published for analysis has less distortion and hence is more useful. Our approximation algorithms for new clustering objectives are of independent interest and could be applicable in other clustering scenarios as well. View details
    Asymptotic Polynomial-Time Approximation Schemes. Handbook of Approximation Algorithms and Metaheuristics.
    Rajeev Motwani
    Liadan O'Callaghan
    Handbook of Approximation Algorithms and Metaheuristics, Teofilo Gonzalez, ed., Chapman and Hall/CRC (2007)
    Preview abstract Approximation schemes are presented for BIN PACKING, including a PAS due to Vega and Lueker, and an FPAS due to Karmakar and Karp. It is shown that the latter can be modified into an approximation algorithm whose absolute error is bounded by a poly-logarithmic function in the value of the optimal solution. View details
    Achieving Anonymity via Clustering
    Tomás Feder
    Krishnaram Kenthapadi
    Samir Khuller
    Rina Panigrahy
    Dilys Thomas
    Proceedings of the 25th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems (PODS) (2006), pp. 153-162
    Preview