Conférencier: Igor Pak, Université de Californie à Los Angeles

As classes of GFs go, we tend to know more about smaller classes than larger ones, think of the progression from rational to algebraic to D-finite to D-algebraic GFs.  The positivity adds another twist on these classes, bringing a host of new problems.  In this talk, I will review some classes of GFs that are of interest in Enumerative Combinatorics but remain understudied, emphasising both larger classes and positivity properties.