Minimum Cost Flows, MDPs, and ?1-Regression in Nearly Linear Time for Dense InstancesShow others and affiliations
2021 (English)In: Proceedings of the Annual ACM Symposium on Theory of Computing, Association for Computing Machinery (ACM) , 2021, p. 859-869Conference paper, Published paper (Refereed)
Abstract [en]
In this paper we provide new randomized algorithms with improved runtimes for solving linear programs with two-sided constraints. In the special case of the minimum cost flow problem on n-vertex m-edge graphs with integer polynomially-bounded costs and capacities we obtain a randomized method which solves the problem in O(m + n1.5) time. This improves upon the previous best runtime of O(m ?n) [Lee-Sidford'14] and, in the special case of unit-capacity maximum flow, improves upon the previous best runtimes of m4/3 + o(1) [Liu-Sidford'20, Kathuria'20] and O(m ?n) [Lee-Sidford'14] for sufficiently dense graphs. In the case of ?1-regression in a matrix with n-columns and m-rows we obtain a randomized method which computes an ?-approximate solution in O(mn + n2.5) time. This yields a randomized method which computes an ?-optimal policy of a discounted Markov Decision Process with S states and, A actions per state in time O(S2 A + S2.5). These methods improve upon the previous best runtimes of methods which depend polylogarithmically on problem parameters, which were O(mn1.5) [Lee-Sidford'15] and O(S2.5 A) [Lee-Sidford'14, Sidford-Wang-Wu-Ye'18] respectively. To obtain this result we introduce two new algorithmic tools of possible independent interest. First, we design a new general interior point method for solving linear programs with two sided constraints which combines techniques from [Lee-Song-Zhang'19, Brand et al.'20] to obtain a robust stochastic method with iteration count nearly the square root of the smaller dimension. Second, to implement this method we provide dynamic data structures for efficiently maintaining approximations to variants of Lewis-weights, a fundamental importance measure for matrices which generalize leverage scores and effective resistances.
Place, publisher, year, edition, pages
Association for Computing Machinery (ACM) , 2021. p. 859-869
Series
Proceedings of the annual ACM Symposium on Theory of Computing, ISSN 0737-8017
Keywords [en]
Data Structure, Interior Point Method, Linear Program, Computation theory, Cost accounting, Flow graphs, Linear programming, Markov processes, Matrix algebra, Stochastic systems, Approximate solution, Dynamic data structure, Effective resistances, Interior-point method, Markov Decision Processes, Minimum cost flow problem, Problem parameters, Randomized Algorithms, Iterative methods
National Category
Computer Sciences Control Engineering
Identifiers
URN: urn:nbn:se:kth:diva-309937DOI: 10.1145/3406325.3451108ISI: 000810492500079Scopus ID: 2-s2.0-85108177126OAI: oai:DiVA.org:kth-309937DiVA, id: diva2:1645919
Conference
53rd Annual ACM SIGACT Symposium on Theory of Computing, STOC 2021, Virtual/Online, 21-25 June 2021
Note
Part of proceedings: ISBN 978-1-4503-8053-9
QC 20220321
2022-03-212022-03-212022-07-15Bibliographically approved