BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Center for Complex Geometry - ECPv6.15.20//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-ORIGINAL-URL:https://ccg.ibs.re.kr
X-WR-CALDESC:Events for Center for Complex Geometry
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Asia/Seoul
BEGIN:STANDARD
TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20240101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250318T150000
DTEND;TZID=Asia/Seoul:20250318T163000
DTSTAMP:20260416T222229
CREATED:20250227T013900Z
LAST-MODIFIED:20250313T070242Z
UID:3641-1742310000-1742315400@ccg.ibs.re.kr
SUMMARY:Lorenzo Barban\, General results on C*-actions on projective varieties
DESCRIPTION:    Speaker\n\n\nLorenzo Barban\nIBS CCG\n\n\n\n\n\n\nIn this lecture series we aim to describe the rich relation between C*-actions on complex normal projetive varieties and the birational maps among the associated geometric quotients. We will begin this first seminar by explaining a motivating example\, called the Atiyah flop. We will then discuss general results on normal projective varieties admitting a C*-action\, such as Sumihiro’s theorem and Białynicki-Birula theorem. We will then conclude by describing how much a C*-action affects the birational geometry of a C*-variety.
URL:https://ccg.ibs.re.kr/event/2025-0318/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Complex Geometry Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250319T150000
DTEND;TZID=Asia/Seoul:20250319T163000
DTSTAMP:20260416T222229
CREATED:20250227T014115Z
LAST-MODIFIED:20250313T070255Z
UID:3643-1742396400-1742401800@ccg.ibs.re.kr
SUMMARY:Lorenzo Barban\, Geometric Invariant Theory for C*-actions
DESCRIPTION:    Speaker\n\n\nLorenzo Barban\nIBS CCG\n\n\n\n\n\n\nIn this second talk\, which is the technical core of the lecture series\, we describe several tools to study C*-actions on projective varieties\, such as the bandwidth\, the AMvsFM Lemma\, and the pruning of a variety. With this\, we will be able to describe the -birational geometry of the- geometric quotients of a C* action on a pair (X\, L)\, with X a normal projective variety and L an ample line bundle on X. We will conclude by characterizing C*-varieties with small bandwidth.
URL:https://ccg.ibs.re.kr/event/2025-0319/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Complex Geometry Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250320T150000
DTEND;TZID=Asia/Seoul:20250320T163000
DTSTAMP:20260416T222229
CREATED:20250227T014235Z
LAST-MODIFIED:20250313T070308Z
UID:3645-1742482800-1742488200@ccg.ibs.re.kr
SUMMARY:Lorenzo Barban\, Geometric realization of birational maps among Mori dream spaces
DESCRIPTION:    Speaker\n\n\nLorenzo Barban\nIBS CCG\n\n\n\n\n\n\nGiven a birational map ϕ among normal projective varieties\, a geometric realization of ϕ is a normal projective C*-variety such that the birational map among geometric quotients parametrizing general orbits coincides with ϕ. Geometric realizations can be thought of as a projective algebraic version of the notion of cobordism coming from Morse theory. After recalling basic facts about Mori dream spaces\, we show that any birational map among Mori dream spaces admits a geometric realization. In the context of toric varieties\, we present a SageMath function to explicitly compute the polytope of the geometric realization. We conclude providing explicit examples of this construction.
URL:https://ccg.ibs.re.kr/event/2025-0320/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Complex Geometry Seminar
END:VEVENT
END:VCALENDAR