Seminars & Colloquia
Sharath Raghvendra
Virginia Tech
"Elegant Algorithms for Bipartite Matching with Applications in Machine Learning"
Friday May 26, 2023 10:00 AM
Location: 3211, EB2 NCSU Centennial Campus
(Visitor parking instructions)
First, I will present a new algorithm for the maximum cardinality matching problem for bipartite graphs with small vertex separators. The classical Hopcroft-Karp algorithm [SICOMP 1973] and the divide and conquer algorithm by Lipton and Tarjan [SICOMP 1980] solve this problem in O(n^1.5 ) time. Our algorithm combines the two approaches resulting in an improved execution time of O(n^1.33 ). This algorithm can be used to compute a bottleneck distance and Levy-Prokhorov distance between low dimensional point sets.
Next, I will present a new algorithm for the minimum-cost bipartite matching problem between two sets of n samples each drawn i.i.d from an unknown two-dimensional distribution. Despite decades of effort, an efficient implementation of the classical Hungarian method that runs in near-quadratic time remains the best-known exact algorithm for this problem. I will present a novel adaptation of the Hungarian algorithm in the geometric divide-and-conquer framework that computes the exact solution in O(n^1.75 ). Our algorithm extends to any fixed dimensional space and is helpful in computing the optimal transport distances that is extensively used in machine learning (training GANs) and statistical inference (the two-sample test).
Finally, I present a novel online algorithm for minimum-cost matching in metric spaces. Here, requests arrive in an online fashion, and we must irrevocably assign a server to serve the request. I present a robust online algorithm that achieves a near-optimal competitive ratio across different request generation models and across different metric spaces thus making substantial progress on a long-standing open problem in online algorithms.
Host: Don Sheehy, CSC