Spring 2015

IT Seminar

Feb. 23, 2015 2:30 pm3:30 pm

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Alexandr Andoni (UC Berkeley)


116 Calvin Lab

Algorithmic design via efficient data representations

The growing scale of data demands novel algorithmic design frameworks that are able to handle modern datasets. In this talk, I will describe how such frameworks emerge from the methods of efficient data representations. The first illustration will be the Nearest Neighbor Search (NNS) problem --- an ubiquitous massive datasets problem that is of key importance in machine learning and other areas.  Its goal is to preprocess a dataset of objects (e.g., images), so that later, given a new query object, one can efficiently return the object most similar to the query. Efficient solutions may be achieved via Locality Sensitive Hashing (LSH), a data representation method that has seen a lot of success in both theory and practice.

I will present the best possible LSH-based algorithm for NNS under the Euclidean distance. Then, I will show a new method that, for the first time, provably outperforms the LSH-based algorithms.

Taking a broader perspective, I will describe other examples where the lens of "efficient data representation" leads to novel fast algorithms. These examples include a classic dynamic programming problem (edit distance), a Linear Program problem (Earth-mover distance), and an algorithmic framework for parallel models of computation (such as MapReduce).