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SUMMARY:Alan Lew (Technion)
DTSTART:20220217T161500Z
DTEND:20220217T170000Z
DTSTAMP:20260422T065933Z
UID:CJCS/62
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/CJCS/62/">Le
 ray numbers of tolerance complexes</a>\nby Alan Lew (Technion) as part of 
 Copenhagen-Jerusalem Combinatorics Seminar\n\n\nAbstract\nIn  this  talk  
 we  will  discuss  the  Leray  and  collapsibility  numbers of  a  simplic
 ial  complex K\,  and  their  role  in Helly-type  theorems  in combinator
 ial geometry.  The Leray number is\, roughly speaking\, the hereditary hom
 ological dimension of K\, while the collapsibility number captures the com
 plexity of dismantling K by sequentially removing free faces from K.\nFoll
 owing the formal definition of these parameters and their connection to th
 e combinatorics of convex sets\, we will introduce the construction of the
  “tolerance complex” of a complex K.  We will explain its relation to 
 a tolerant version of Helly’s theorem due to Montejano and Oliveros and 
 present new results on the Leray numbers of these complexes.\nThe talk is 
 based on joint work with Minki Kim.\n
LOCATION:https://researchseminars.org/talk/CJCS/62/
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