BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Elizabeth Milićević (Haverford College)
DTSTART:20241011T180000Z
DTEND:20241011T190000Z
DTSTAMP:20260415T110830Z
UID:MAAGC2024/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/MAAGC2024/1/
 ">Crystal chute moves on pipe dreams</a>\nby Elizabeth Milićević (Haverf
 ord College) as part of MAAGC 2024\n\n\nAbstract\nSchubert polynomials rep
 resent a basis for the cohomology of the complete flag variety. In this co
 ntext\, Schubert polynomials are generating functions over various combina
 torial objects\, such as rc-graphs or reduced pipe dreams.  By restricting
  Bergeron and Billey’s chute moves on rc-graphs\, we define a Demazure c
 rystal structure on the monomials of a Schubert polynomial.  As a conseque
 nce\, we provide a new method for decomposing Schubert polynomials as sums
  of key polynomials.  These results complement related work of Assaf and S
 chilling via reduced factorizations with cutoff\, as well as Lenart’s co
 plactic operators on biwords.  No prior knowledge of either key polynomial
 s or crystals will be assumed in this talk.\n
LOCATION:https://researchseminars.org/talk/MAAGC2024/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Swee Hong Chan (Rutgers University)
DTSTART:20241011T200000Z
DTEND:20241011T210000Z
DTSTAMP:20260415T110830Z
UID:MAAGC2024/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/MAAGC2024/2/
 ">Complexity of log-concave inequalities in matroids</a>\nby Swee Hong Cha
 n (Rutgers University) as part of MAAGC 2024\n\n\nAbstract\nA sequence of 
 nonnegative real numbers a_1\, a_2\, ...\, a_n\, is log-concave if a_i^2 <
 = a_{i-1} a_{i+1} for all i ranging from 2 to n-1. Examples of log-concave
  inequalities range from inequalities that are readily provable\, such as 
 the binomial coefficients a_i = \\binom{n}{i}\, to intricate inequalities 
 that have taken decades to resolve\, such as the number of independent set
 s a_i in a matroid M with i elements (otherwise known as the first Mason's
  conjecture\; and was resolved by June Huh in 2010s in a remarkable breakt
 hrough). It is then natural to ask if it can be shown that the latter type
  of inequalities is intrinsically more challenging than the former. In thi
 s talk\, we provide a rigorous framework to answer this type of questions\
 , by employing a combination of combinatorics\, complexity theory\, and ge
 ometry. This is a joint work with Igor Pak.\n
LOCATION:https://researchseminars.org/talk/MAAGC2024/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Minyoung Jeon (University of Georgia)
DTSTART:20241012T130000Z
DTEND:20241012T140000Z
DTSTAMP:20260415T110830Z
UID:MAAGC2024/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/MAAGC2024/3/
 ">Mather classes via small resolutions</a>\nby Minyoung Jeon (University o
 f Georgia) as part of MAAGC 2024\n\n\nAbstract\nThe Chern-Mather class is 
 a characteristic class\, generalizing the Chern class of a tangent bundle 
 of a nonsingular variety to a singular variety. It uses the Nash-blowup fo
 r a singular variety instead of the tangent bundle. In this talk\, we cons
 ider Schubert varieties\, known as singular varieties in most cases\, in t
 he even orthogonal Grassmannians and discuss the work computing the Chern-
 Mather class of the Schubert varieties by the use of the small resolution 
 of Sankaran and Vanchinathan with Jones’ technique. We also describe the
  Kazhdan-Lusztig class of Schubert varieties in Lagrangian Grassmannians\,
  as an analogous result. If time permitted\, we discuss the application of
  Jones’s method on K-orbit closures in flag varieties\, as a joint work 
 with Graham and Scott.\n
LOCATION:https://researchseminars.org/talk/MAAGC2024/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sam Hopkins (Howard University)
DTSTART:20241012T150000Z
DTEND:20241012T160000Z
DTSTAMP:20260415T110830Z
UID:MAAGC2024/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/MAAGC2024/4/
 ">Upho posets</a>\nby Sam Hopkins (Howard University) as part of MAAGC 202
 4\n\n\nAbstract\nA partially ordered set is called upper homogeneous\, or 
 “upho\,” if every principal order filter is isomorphic to the whole po
 set. This class of fractal-like posets was recently introduced by Stanley.
  Our first observation is that the rank generating function of a (finite t
 ype N-graded) upho poset is the reciprocal of its characteristic generatin
 g function. This means that each upho lattice has associated to it a finit
 e graded lattice\, called its core\, that determines its rank generating f
 unction. With an eye towards classifying upho lattices\, we investigate wh
 ich finite graded lattices arise as cores\, providing both positive and ne
 gative results. Our overall goal for this talk is to advertise upho posets
 \, and especially upho lattices\, which we believe are a natural and rich 
 class of posets deserving of further attention. Essentially no background 
 knowledge will be assumed\, and we also hope to highlight several open pro
 blems.\n
LOCATION:https://researchseminars.org/talk/MAAGC2024/4/
END:VEVENT
END:VCALENDAR