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TZID:Asia/Seoul
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TZOFFSETFROM:+0900
TZOFFSETTO:+0900
TZNAME:KST
DTSTART:20250101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Seoul:20260701T163000
DTEND;TZID=Asia/Seoul:20260701T173000
DTSTAMP:20260621T160131Z
CREATED:20260621T160131Z
LAST-MODIFIED:20260621T160131Z
UID:4601-1782923400-1782927000@ccg.ibs.re.kr
SUMMARY:Birational contractions of \(\overline{\mathrm{M}}_{g\,n}\) and their dependence on the characteristic
DESCRIPTION:    Speaker\n\n\nDaebeom Choi\nUniversity of Pennsylvania\n\n\n\n\n\n\nIn this talk\, we discuss the existence and nonexistence of certain birational contractions of \(\overline{\mathrm{M}}_{g\,n}\). Somewhat surprisingly\, this depends on the characteristic of the base field: many such contractions exist only in positive characteristic. We present a precise form of this phenomenon and discuss two examples that highlight the difference between characteristic zero and positive characteristic. The first is a simple and explicit contraction that exists only in positive characteristic\, and the second is a modular interpretation of the morphisms associated with psi classes on \(\overline{\mathrm{M}}_{1\,n}\). We also offer some speculation on why such characteristic-dependent phenomena arise.
URL:https://ccg.ibs.re.kr/event/birational-contractions-of-overlinemathrmm_gn-and-their-dependence-on-the-characteristic/
LOCATION:B236-1\, IBS\, Korea\, Republic of
CATEGORIES:Algebraic Geometry Seminar
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