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Seminarios ISCI: “First-order Methods for Constrained Continuous Optimization”, Haihao Lu, U. of Chicago Booth School of Business

27Mar

13:30, Sala 401, Beauchef 851, Santiago.

Invitado: Haihao Lu, University of Chicago Booth School of Business.

Abstract

In this talk, I will talk about the recent ongoing trend of research on new first-order methods for scaling up and speeding up constrained continuous optimization. Continuous constrained optimization (CCO), including linear programming (LP), quadratic programming (QP), second-order cone programming (SOCP), semi-definite programming (SDP), and nonlinear programming (NLP), is a fundamental tool in operations research with wide applications in practice. The state-of-the-art solvers for CCO are mature and reliable at delivering accurate solutions. However, these methods do not scale up with modern computational resources and thus are unsuitable for big data applications. The computational bottleneck was the matrix factorization, which usually requires significant memory usage and cannot be directly applied with modern computing resources. In contrast, first-order methods (FOMs) only require matrix-vector multiplications, which work well on these modern computing infrastructures and have massively accelerated machine learning training during the last 15 years. This ongoing line of research aims to scale up CCO 1000 times and speed up CCO 10-100 times by using FOMs and modern computational resources, i.e., distributed computing and/or GPUs. With an example of LP, I’ll discuss how we can achieve this by explaining: (i) the intuitions about designing FOMs for LP; (ii) theoretical results, including complexity theory, condition number theory, infeasibility detection, and how theory can lead to better computation and better understanding of the algorithm’s performance; (iii) numerical results of the proposed algorithm on large instances and modern computing architectures; (iv) large-scale applications. If time permits, I’ll also talk about our recent results on QP.  I’ll conclude the talk with open questions and new directions on this line of research.

Organiza: Instituto Sistemas Complejos de Ingeniería (ISCI).


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