2019 Principles of Distributed Computing Doctoral Dissertation Award

The winner of the 2019 Principles of Distributed Computing Doctoral Dissertation Award is Dr. Sepehr Assadi for his dissertation Combinatorial Optimization on Massive Datasets: Streaming, Distributed, and Massively Parallel Computation, written under the supervision of Prof. Sanjeev Khanna at the University of Pennsylvania. The thesis resolves a number of long-standing problems in the exciting and still relatively new area of sublinear computation. The area of sublinear computation focuses on design of algorithms that use sublinear space, time, or communication to solve global optimization problems on very large datasets. In addition to addressing a wide range of different problems, comprising graph optimization problems (matching, vertex cover, and connectivity), submodular optimization (set cover and maximum coverage), and resource-constrained optimization (combinatorial auctions and learning), these problems are studied in three different models of computation, namely, streaming algorithms, multiparty communication, and massively parallel computation (MPC). The thesis also reveals interesting relations between these different models, including generic algorithmic and analysis techniques that can be applied in all of them. For many fundamental optimization problems, the thesis gives asymptotically matching algorithmic and intractability results, completely resolving several long-standing problems. This is accomplished by using a broad spectrum of mathematical methods in very detailed and intricate proofs. In addition to a wide variety of classic techniques, ranging from graph theory, combinatorics, probability, linear algebra and calculus, it also makes heavy use of communication complexity and information theory, for example. Sepehr's dissertation work has been published in a remarkably large number of top-conference papers. It received multiple best paper awards and multiple special issue invitations, as well as two invitations to the Highlights of Algorithms (HALG) conference. Due to its contributions to the field of distributed computing and all the merits mentioned above, the award committee unanimously selected this thesis as the winner of the 2019 Principles of Distributed Computing Doctoral Dissertation Award.