The Tutte Polynomial of a Morphism of Matroids 5. Derivatives as   Generating Functions of Tutte Activities
  We show that in an ordered matroid the partial derivative \partial^{p+q}t/\partialx^p\partialyq of the Tutte polynomial is p!q! times the generating function of activities of subsets with corank p and nullity q. More generally, this property holds for the 3-variable Tutte polynomial of a matroid perspective. 
Michel Las Vergnas
math.CO