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SUMMARY:Michael Shulman (University of San Diego)
DTSTART:20260323T160000Z
DTEND:20260323T170000Z
DTSTAMP:20260422T140000Z
UID:BilTop/132
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/BilTop/132/"
 >Doubly weak double categories</a>\nby Michael Shulman (University of San 
 Diego) as part of Bilkent Topology Seminar\n\nLecture held in SA 141.\n\nA
 bstract\nDouble categories are a two-dimensional categorical structure wit
 h two different classes of 1-cells\, and 2-cells shaped like a square.  It
  is easy to define double categories with strict composition like 2-catego
 ries\; but double categories with weak composition analogous to bicategori
 es\, for both kinds of 1-cells\, are surprisingly difficult to define.  We
  give a simple definition of "doubly weak double categories" by using the 
 notion of "implicit" categorical structure\, in which composition is not a
 n algebraic operation at all but is witnessed by isomorphisms.  Then we di
 scuss various ways in which this can be made algebraic.  This is joint wor
 k with Aaron David Fairbanks.\n
LOCATION:https://researchseminars.org/talk/BilTop/132/
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