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Explore latest developments in machine learning algorithms at the 49th ACM STOC Symposium. Discover innovative methods like FastCubic and Katyusha, offering accelerated solutions for optimization and stochastic gradient methods. Dive into trace reconstruction techniques for noisy observations with cutting-edge research presented in Montreal.
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STOC: Annual ACM Symposium on the Theory of Computing Ivan Jovetić
Conference summary • 49th edition • June 19th to June 23rd, 2017 in Montreal, Canada • 103 papers accepted and presented, as well as 8 invited paper talks • Typical topics of interest for STOC papers: optimization problems, approximation algorithms, machine learning etc.
Finding Approximate Local MinimaFaster than Gradient Descent • FastCubic algorithm • FastCubic finds approximate local minima faster than first-order methods despite them only finding critical points • Applies to non-convex objectives arising in machine learning, e.g. training a neural network
Katyusha: The First Direct Acceleration of Stochastic Gradient Methods • In large-scale machine learning the number of data examples is very large • stochastic gradient iterations • Stochastic gradient methods are used because they only need one example per iteration to form an estimator of the full gradient • Nesterov’s momentum trick doesn’t necessarily accelerate methods in a stochastic setting • Katyusha is a direct, primal-only stochastic gradient method that uses “negative momentum” to fix the issue
Trace Reconstruction with Samples • In trace reconstruction problem, the goal is to reconstruct an unknown bit string x from multiple noisy observations of x • Focused on the case where the noise is due to x going through the deletion channel • Deletion channel deletes each bit with probability q, resulting in contracted x̃ • How many independent copies of x̃ are needed to reconstruct original x with high probability?
References • Zeyuan Allen-Zhu. 2017. Katyusha: The First Direct Acceleration of Stochastic Gradient Methods. InProceedings of 49th Annual ACM SIGACT Symposium on the Theory of Computing, Montreal, Canada, June 2017 (STOC’17). DOI: 10.1145/3055399.305544 • NamanAgarwal, Zeyuan Allen-Zhu, Brian Bullins, EladHazan, and TengyuMa. 2017. Finding Approximate Local MinimaFaster than Gradient Descent. InProceedings of 49th Annual ACM SIGACTSymposium on the Theory of Computing, Montreal, Canada, June 2017 (STOC’17). DOI: 10.1145/3055399.305546 • FedorNazarov and Yuval Peres. 2017. Trace Reconstruction with Samples. In Proceedings of 49th Annual ACM SIGACT Symposium on the Theory of Computing, Montreal, Canada, June 2017 (STOC’17). DOI: 10.1145/3055399.305549