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比利时vs摩洛哥足彩 ,
university of california san diego

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math 269 - combinatorics

josh hallam

loyola marymount university

whitney duals of partially ordered sets

abstract:

to each graded poset one can associate two sequences of numbers: the whitney numbers of the first kind and the whitney numbers of the second kind. one sequence keeps track of the m$\ddot{\text{o}}$bius function at each rank level and the other keeps track of the number of elements at each rank level. we say if $p$ and $q$ are whitney duals if the whitney numbers of the first kind of $p$ are the whitney numbers of the second kind of $q$ and vice-versa. in this talk, we will discuss a method to construct whitney duals. this method uses a new type of edge labeling as well as quotient posets. for posets which have this type of labeling, one can construct a simplicity complex whose $f$-vector encodes the whitney numbers of the second kind of this poset. time permitting, we will discuss this complex. this is joint work with rafael s. gonz\'alez d'le\'on.

host: brendon rhoades

october 30, 2018

4:00 pm

ap&m 6402

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