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DTSTART;TZID=America/Toronto:20250411T153000
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URL:/combinatorics-and-optimization/events/tutte-colloq
 uium-ricardo-fukasawa-1
SUMMARY:Tutte colloquium-Ricardo Fukasawa
CLASS:PUBLIC
DESCRIPTION:Summary \n\nTITLE: Exact algorithms for combinatorial interdic
 tion problems\n\nSPEAKER:\n Ricardo Fukasawa\n\nAFFILIATION:\n University 
 of À¶Ý®ÊÓƵ\n\nLOCATION:\n MC 5501\n\nABSTRACT: Typical optimization parad
 igms involve a single decision\nmaker that can control all variables invol
 ved. However\, several\npractical situations involve multiple (potentially
  adversarial)\ndecision makers. Bilevel optimization is a field that invol
 ves two\ndecision makers. The key paradigm is that an upper-level decision
 \nmaker acts first and after observing the upper-level decisions\, a\nlowe
 r level decision maker optimizes their own objective. One\nparticular impo
 rtant instance of such problems are so-called\ninterdiction problems\, whe
 re the upper-level decision is to try and\nforbid access to some decisions
  by the lower level and the goal of the\nupper level is to make the most i
 mpact into the lower-level decisions.\nThese problems are\, in general $\\
 Sigma^P_2$-hard (likely harder than\nNP-hard). \n\n \n\nIn this talk I w
 ill present recent work on improving significantly on\nstate-of-the-art ex
 act algorithms to obtain optimal solutions to some\ncombinatorial interdic
 tion problems. Despite the hardness results\, our\nalgorithm can solve ins
 tances consistently in a short amount of time.\nWe also generalize our alg
 orithms to propose a framework that could be\napplied to other similar pro
 blems\, by deriving relaxations based on\nlooking at these problems as gam
 es and performing operations on such\ngames. \n\n \n\nThis is joint work
  with Noah Weninger.\n\n \n\n \n 
DTSTAMP:20250705T163715Z
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