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SUMMARY:Osamu Fujino (Osaka University)
DTSTART:20210121T100000Z
DTEND:20210121T110000Z
DTSTAMP:20260423T021356Z
UID:ZAG/88
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/ZAG/88/">On 
 extremal contractions of log canonical pairs</a>\nby Osamu Fujino (Osaka U
 niversity) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\
 nThe cone and contraction theorem holds for projective log canonical pairs
 . Let us consider an extremal contraction morphism of a log canonical pair
 . We prove that every irreducible component of the exceptional locus is un
 iruled. This result was first proved by Yujiro Kawamata for kawamata log t
 erminal pairs. His proof uses a relative Kawamata--Viehweg vanishing theor
 em for projective bimeromorphic morphisms of complex analytic spaces and d
 oes not work for log canonical pairs. Our approach is based on the theory 
 of quasi-log schemes and can be applied to more general settings. We need 
 a semipositivity theorem coming from the theory of variations of mixed Hod
 ge structure. We note that we do not use the minimal model program.\n
LOCATION:https://researchseminars.org/talk/ZAG/88/
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