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UID:20260913T091421EDT-4666zuvRpk@132.216.98.100
DTSTAMP:20260913T131421Z
DESCRIPTION:Title: Cusp Singularities\n\n \n\nAbstract: In 1884\, Klein ini
 tiated the study of rational double points (RDPs)\, a special class of sur
 face singularities which are in bijection with the simply-laced Dynkin dia
 grams. Over the course of the 20th century\, du Val\, Artin\, Tyurina\, Br
 ieskorn\, and others intensively studied their properties\, in particular 
 determining their adjacencies---the other singularities to which an RDP de
 forms. The answer: One RDP deforms to another if and only if the Dynkin di
 agram of the latter embeds into the Dynkin diagram of the former. The next
  stage of complexity is the class of elliptic surface singularities. Their
  deformation theory\, initially studied by Laufer in 1973\, was largely de
 termined by the mid 1980's by work of Pinkham\, Wahl\, Looijenga\, Friedma
 n and others. The exception was a conjecture of Looijenga's regarding smoo
 thability of cusp singularities---surface singularities whose resolution i
 s a cycle of rational curves. I will describe a proof of Looijenga's conje
 cture which connects the problem to symplectic geometry via mirror symmetr
 y\, and summarize some recent work with Friedman determining adjacencies o
 f a cusp singularity.\n
DTSTART:20180118T210000Z
DTEND:20180118T220000Z
LOCATION:Room 1205\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue
  Sherbrooke Ouest
SUMMARY:Philip Engel\, Harvard University 
URL:https://www.mcgill.ca/mathstat/channels/event/philip-engel-harvard-univ
 ersity-283886
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