Casey Tompkins, Extremal forbidden poset problems in Boolean and linear lattices

Extending the classical theorem of Sperner on the maximum size of an antichain in the Boolean lattice, Katona and Tarján introduced a general extremal function $La(n,P)$, defined to be the maximum size of a family of subsets of $[n]$ which does not contain a given poset $P$ among its containment relations.  In this talk, I will discuss what is known about the behavior of $La(n,P)$ and its natural extension to the lattice of subspaces of a vector space over a finite field.  In particular, I will highlight some recent joint work with Jimeng Xiao.  Many open problems will also be discussed.