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DTSTART:20240310T070000
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DTSTART:20231105T060000
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DTSTART;TZID=America/Toronto:20241031T140000
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URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-joseph
SUMMARY:Algebraic and enumerative combinatorics seminar-Joseph Fluegemann
CLASS:PUBLIC
DESCRIPTION:TITLE:Smooth points on positroid varieties and planar N=4\nsupe
 rsymmetric Yang-Mills theory\n\nSpeaker\n Joseph Fluegemann\n\nAffiliation
 \n University of Waterloo\n\nLocation\n MC 5479\n\n ABSTRACT: Positroid v
 arieties are subvarieties in the Grassmannian\ndefined by cyclic rank cond
 itions and which are related to Schubert\nvarieties. We will provide a cri
 terion for whether positroid varieties\nare smooth at certain distinguishe
 d points\, and we will show that this\ninformation is sufficient to determ
 ine smoothness for the entire\npositroid variety. This will involve lookin
 g at combinatorial diagrams\ncalled \"affine pipe dreams.\" We can also fo
 rm a partial order on\npositroid varieties given by deletion and contracti
 on\, such that there\nis closure for smooth positroid varieties\, and we w
 ill characterize\nthe minimal singular elements in this order. Finally\, w
 e will discuss\na couple of connections between the techniques of this wor
 k and planar\nN=4\n\nSYM: the BCFW bridge decomposition and inverse soft f
 actors.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT T
 HE\nBEGINNING GRADUATE LEVEL STARTING AT 1PM\,
DTSTAMP:20260403T083834Z
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