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DTSTART:20250309T070000
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DTSTART:20251102T060000
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DTSTART;TZID=America/Toronto:20260205T143000
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URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-jonathan-0
SUMMARY:Algebraic and enumerative combinatorics seminar - Jonathan\nBoretsk
 y-Excluding a line from positroids
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Jonathan Boretsky\n\nAFFILIATION:\n McGill Universit
 y\n\nLOCATION:\n MC 5417\n\nABSTRACT: For all positive integers l and r\,
  we determine the maximum\nnumber of elements of a simple rank-r positroid
  without the rank-2\nuniform matroid U(2\, l+2) as a minor\, and character
 ize the matroids\nwith the maximum number of elements. This result continu
 es a long line\nof research into upper bounds on the number of elements of
  matroids\nfrom various classes that forbid U(2\, l+2) as a minor\, includ
 ing works\nof Kung\, of Geelen–Nelson\, and of Geelen–Nelson–Walsh. 
 This is\nthe first paper to study positroids in this context\, and it sugg
 ests\nmethods to study similar problems for other classes of matroids\, su
 ch\nas gammoids or base-orderable matroids. This project is based on joint
 \nwork with Zach Walsh.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVAN
 T BACKGROUND AT THE\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM.
DTSTAMP:20260402T155248Z
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