Grassmannian trilogarithms
  Some time ago the first author suggested two different constructions of Grassmannian n-logarithms. One of them works for all n, but its motivic nature is hidden. The other is a motivic but so far available only for n=2,3,4. We derived some general results about the first construction of Grassmannian polylogarithms, and found an explicit relation between the two constructions of the Grassmannian trilogarithms. 
A.B. Goncharov, J. Zhao