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UID:20251110T001225EST-8955Dx6LIB@132.216.98.100
DTSTAMP:20251110T051225Z
DESCRIPTION:Title: Brambles\, stack number and topological overlap.\n\nAbst
 ract: A (strict) bramble in a graph G is a collection of subgraphs of G su
 ch that the union of any number of them is connected. The order of a bramb
 le is the smallest size of a set of vertices that intersects each of the s
 ubgraphs in it. Brambles have long been part of the graph minor theory too
 lkit\, in particular\, because a bramble of high order is an obstruction t
 o existence of a low width tree decomposition. We will discuss high dimens
 ional analogues of brambles. In particular\, we show that an d-dimensional
  bramble of high order in a d-dimensional simplicial complex X is an obstr
 uction to existence of a low multiplicity continuous map from X to R^d (an
 d more generally to any d-dimensional contractible complex). This can be s
 een as a qualitative variant of Gromov's topological overlap theorem. As a
 n application\, we construct the first explicit example of a graph family 
 with bounded maximum degree and unbounded stack-number. Based in part on j
 oint work with David Eppstein\, Robert Hickingbotham\, Laura Merker\, Mich
 ał T. Seweryn and David R. Wood.\n
DTSTART:20240221T200000Z
DTEND:20240221T210000Z
LOCATION:Room 920\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue 
 Sherbrooke Ouest
SUMMARY:Sergey Norin (º£½Ç¾«Æ·ºÚÁÏ)
URL:/mathstat/channels/event/sergey-norin-mcgill-unive
 rsity-355497
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