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X-WR-CALNAME:Center for Complex Geometry
X-ORIGINAL-URL:https://ccg.ibs.re.kr
X-WR-CALDESC:Events for Center for Complex Geometry
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BEGIN:VTIMEZONE
TZID:Asia/Seoul
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TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20240101T000000
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BEGIN:VEVENT
DTSTART;VALUE=DATE:20250301
DTEND;VALUE=DATE:20260216
DTSTAMP:20260415T114607
CREATED:20250304T080834Z
LAST-MODIFIED:20250304T081528Z
UID:3669-1740787200-1771199999@ccg.ibs.re.kr
SUMMARY:Ngoc Cuong Nguyen (KAIST)
DESCRIPTION:Ngoc Cuong Nguyen\nVisitor (2025.3.1-2026.2.15) from KAIST\nOffice: B248
URL:https://ccg.ibs.re.kr/event/250301-260215/
CATEGORIES:Visitors
ATTACH;FMTTYPE=image/jpeg:https://ccg.ibs.re.kr/wp-content/uploads/2025/03/ncnguyen_rescaled-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250807T140000
DTEND;TZID=Asia/Seoul:20250807T150000
DTSTAMP:20260415T114607
CREATED:20250721T120346Z
LAST-MODIFIED:20250721T120346Z
UID:3933-1754575200-1754578800@ccg.ibs.re.kr
SUMMARY:Hyukmoon Choi\, Equivariant compactification structures on smooth projective horospherical varieties of Picard number 1
DESCRIPTION:    Speaker\n\n\nHyukmoon Choi\nIBS CCG and KAIST\n\n\n\n\n\n\nA projective variety V is an equivariant compactification of an algebraic group G if there exists an algebraic G-action on V with a Zariski open orbit O\, which is equivariantly biregular to G. Such a G-action is called an equivariant compactification (EC) structure on V. For a smooth nonhomogeneous projective horospherical variety X of Picard number 1\, and for a suitable nilpotent subgroup N of the automorphism group of X\, we show that X admits an EC structure of N and that any two EC structures of N on X are isomorphic.
URL:https://ccg.ibs.re.kr/event/2025-0807/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Complex Geometry Seminar
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250827T163000
DTEND;TZID=Asia/Seoul:20250827T173000
DTSTAMP:20260415T114607
CREATED:20250807T081010Z
LAST-MODIFIED:20250807T081429Z
UID:3987-1756312200-1756315800@ccg.ibs.re.kr
SUMMARY:Makoto Enokizono\, Normal stable degenerations of Noether-Horikawa surfaces
DESCRIPTION:    Speaker\n\n\nMakoto Enokizono\nUniversity of Tokyo\n\n\n\n\n\n\nNoether-Horikawa surfaces are surfaces of general type satisfying the equation K2=2pg−4\, which represents the equality of the Noether inequality K2≥2pg−4 for surfaces of general type. In the 1970s\, Horikawa conducted a detailed study of smooth Noether-Horikawa surfaces\, providing a classification of these surfaces and describing their moduli spaces.\nIn this talk\, I will present an explicit classification of normal stable degenerations of Noether-Horikawa surfaces. Specifically\, I will discuss the following results:\n(1) Classification of Noether-Horikawa surfaces with Q-Gorenstein smoothable log canonical singularities.\n(2) Criterion for determining the (global) Q-Gorenstein smoothability of the surfaces described in (1).\n(3) Description of the KSBA moduli spaces for Q-Gorenstein smoothable normal stable Noether-Horikawa surfaces.\nThis is joint work with Hiroto Akaike\, Masafumi Hattori and Yuki Koto.
URL:https://ccg.ibs.re.kr/event/2025-0827/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Algebraic Geometry Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250828T150000
DTEND;TZID=Asia/Seoul:20250828T160000
DTSTAMP:20260415T114607
CREATED:20250731T053718Z
LAST-MODIFIED:20250807T081201Z
UID:3972-1756393200-1756396800@ccg.ibs.re.kr
SUMMARY:Doyoung Choi\, Singularities and syzygies of secant varieties of smooth projective varieties
DESCRIPTION:    Speaker\n\n\nDoyoung Choi\nKAIST / IBS\n\n\n\n\n\n\nWe study the higher secant varieties of a smooth projective variety embedded in projective space. We prove that when the variety is a surface and the embedding line bundle is sufficiently positive\, these varieties are normal with Du Bois singularities and the syzygies of their defining ideals are linear to the expected order. We show that the cohomology of the structure sheaf of the surface completely determines whether the singularities of its secant varieties are Cohen-Macaulay or rational. We also prove analogous results when the dimension of the original variety is higher and the secant order is low\, and by contrast we prove a result that strongly implies these statements do not generalize to higher dimensional varieties when the secant order is high. Finally\, we deduce a complementary result characterizing the ideal of secant varieties of a surface in terms of the symbolic powers of the ideal of the surface itself\, and we include a theorem concerning the weight one syzygies of an embedded surface — analogous to the gonality conjecture for curves — which we discovered as a natural application of our techniques.
URL:https://ccg.ibs.re.kr/event/2025-0828/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Algebraic Geometry Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20250828T163000
DTEND;TZID=Asia/Seoul:20250828T173000
DTSTAMP:20260415T114607
CREATED:20250731T053916Z
LAST-MODIFIED:20250807T081139Z
UID:3975-1756398600-1756402200@ccg.ibs.re.kr
SUMMARY:Haesong Seo\, Algebraic hyperbolicity of adjoint linear systems on spherical varieties
DESCRIPTION:    Speaker\n\n\nHaesong Seo\nKAIST / IBS\n\n\n\n\n\n\nA projective manifold is called hyperbolic if it does not admit an entire map from the complex plane. Demailly proved that hyperbolic manifolds are algebraically hyperbolic\, meaning that there are degree bounds for curves in terms of their genera. It is a highly challenging problem to determine whether a given variety is algebraically hyperbolic or not. In this talk\, we prove that a very general hypersurface in an adjoint linear system on a spherical variety is algebraically hyperbolic outside the boundary. This is based on a joint work with Dr. Minseong Kwon.
URL:https://ccg.ibs.re.kr/event/2025-0828-2/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Algebraic Geometry Seminar
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