Decomposition theorem for the cd-index of Gorenstein* posets
  We prove a decomposition theorem for the cd-index of a Gorenstein* poset analogous to the decomposition theorem for the intersection cohomology of a toric variety. From this we settle a conjecture of Stanley that the cd-index of Gorenstein* lattices is minimized on Boolean algebras. 
Richard Ehrenborg, Kalle Karu