Supercharacters, symmetric functions in noncommuting variables, and related Hopf algebras
arXiv:1009.4134 · doi:10.1016/j.aim.2011.12.024
Abstract
We identify two seemingly disparate structures: supercharacters, a useful way of doing Fourier analysis on the group of unipotent uppertriangular matrices with coefficients in a finite field, and the ring of symmetric functions in noncommuting variables. Each is a Hopf algebra and the two are isomorphic as such. This allows developments in each to be transferred. The identification suggests a rich class of examples for the emerging field of combinatorial Hopf algebras.
To Appear in Advances in Mathematics (2012), 23 pages