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SUMMARY:Chris Lazda (Warwick)
DTSTART:20200506T150000Z
DTEND:20200506T160000Z
DTSTAMP:20260418T063705Z
UID:LNTS/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/LNTS/3/">A N
 éron-Ogg-Shafarevich criterion for K3 surfaces</a>\nby Chris Lazda (Warwi
 ck) as part of London number theory seminar\n\n\nAbstract\nThe naive analo
 gue of the Néron–Ogg–Shafarevich criterion fails for K3 surfaces\, th
 at is\, there exist K3 surfaces over Henselian\, discretely valued fields 
 K\, with unramified etale cohomology groups\, but which do not admit good 
 reduction over K. Assuming potential semi-stable reduction\, I will show h
 ow to correct this by proving that a K3 surface has good reduction if and 
 only if its second cohomology is unramified\, and the associated Galois re
 presentation over the residue field coincides with the second cohomology o
 f a certain “canonical reduction” of X. This is joint work with B. Chi
 arellotto and C. Liedtke.\n
LOCATION:https://researchseminars.org/talk/LNTS/3/
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