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DTSTART;TZID=America/Toronto:20250411T153000
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URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-ricardo-fukasawa-1
SUMMARY:Tutte colloquium-Ricardo Fukasawa
CLASS:PUBLIC
DESCRIPTION:TITLE: Exact algorithms for combinatorial interdiction problem
 s\n\nSPEAKER:\n Ricardo Fukasawa\n\nAFFILIATION:\n University of Waterloo\
 n\nLOCATION:\n MC 5501\n\nABSTRACT: Typical optimization paradigms involve
  a single decision\nmaker that can control all variables involved. However
 \, several\npractical situations involve multiple (potentially adversarial
 )\ndecision makers. Bilevel optimization is a field that involves two\ndec
 ision makers. The key paradigm is that an upper-level decision\nmaker acts
  first and after observing the upper-level decisions\, a\nlower level deci
 sion maker optimizes their own objective. One\nparticular important instan
 ce of such problems are so-called\ninterdiction problems\, where the upper
 -level decision is to try and\nforbid access to some decisions by the lowe
 r level and the goal of the\nupper level is to make the most impact into t
 he lower-level decisions.\nThese problems are\, in general $\\Sigma^P_2$-h
 ard (likely harder than\nNP-hard). \n\n \n\nIn this talk I will present 
 recent work on improving significantly on\nstate-of-the-art exact algorith
 ms to obtain optimal solutions to some\ncombinatorial interdiction problem
 s. Despite the hardness results\, our\nalgorithm can solve instances consi
 stently in a short amount of time.\nWe also generalize our algorithms to p
 ropose a framework that could be\napplied to other similar problems\, by d
 eriving relaxations based on\nlooking at these problems as games and perfo
 rming operations on such\ngames. \n\n \n\nThis is joint work with Noah W
 eninger.\n\n \n\n 
DTSTAMP:20260406T204402Z
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