JCT
2006
13 years 4 months ago
2006
We prove a combinatorial formula conjectured by Loehr and Warrington for the coefficient of the sign character in (pn). Here denotes the Bergeron-Garsia nabla operator, and pn is a...
EJC
2010
13 years 5 months ago
2010
We give a combinatorial formula for the inverses of the alternating sums of free quasi-symmetric functions of the form F(I) where I runs over compositions with parts in a prescribe...