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PRODID:-//Discrete Mathematics Group - ECPv6.16.1//NONSGML v1.0//EN
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X-ORIGINAL-URL:https://dimag.ibs.re.kr
X-WR-CALDESC:Events for Discrete Mathematics Group
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X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Asia/Seoul
BEGIN:STANDARD
TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20210101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20221013T161500
DTEND;TZID=Asia/Seoul:20221013T171500
DTSTAMP:20260513T165610
CREATED:20221006T054719Z
LAST-MODIFIED:20240705T171138Z
UID:6264-1665677700-1665681300@dimag.ibs.re.kr
SUMMARY:Xavier Goaoc\, Order types and their symmetries
DESCRIPTION:Order types are a combinatorial classification of finite point sets used in discrete and computational geometry. This talk will give an introduction to these objects and their analogue for the projective plane\, with an emphasis on their symmetry groups. \nThis is joint work with Emo Welzl.
URL:https://dimag.ibs.re.kr/event/2022-10-13/
LOCATION:Room 1501\, Bldg. E6-1\, KAIST
CATEGORIES:Colloquium
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20221027T161500
DTEND;TZID=Asia/Seoul:20221027T171500
DTSTAMP:20260513T165610
CREATED:20221012T134118Z
LAST-MODIFIED:20240705T171136Z
UID:6311-1666887300-1666890900@dimag.ibs.re.kr
SUMMARY:Dabeen Lee (이다빈)\, Non-smooth and Hölder-smooth submodular optimization
DESCRIPTION:We study the problem of maximizing a continuous DR-submodular function that is not necessarily smooth. We prove that the continuous greedy algorithm achieves an [(1−1/e)OPT−ϵ] guarantee when the function is monotone and Hölder-smooth\, meaning that it admits a Hölder-continuous gradient. For functions that are non-differentiable or non-smooth\, we propose a variant of the mirror-prox algorithm that attains an [(1/2)OPT−ϵ] guarantee. We apply our algorithmic frameworks to robust submodular maximization and distributionally robust submodular maximization under Wasserstein ambiguity. In particular\, the mirror-prox method applies to robust submodular maximization to obtain a single feasible solution whose value is at least (1/2)OPT−ϵ. For distributionally robust maximization under Wasserstein ambiguity\, we deduce and work over a submodular-convex maximin reformulation whose objective function is Hölder-smooth\, for which we may apply both the continuous greedy method and the mirror-prox method.\nJoint work with Duksang Lee and Nam Ho-Ngyuen.
URL:https://dimag.ibs.re.kr/event/2022-10-27/
LOCATION:Room 1501\, Bldg. E6-1\, KAIST
CATEGORIES:Colloquium
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