Conjectural positivity of Chern-Schwartz-MacPherson classes for Richardson cells

Abstract: Following some work of Aluffi-Mihalcea-Sch\"{u}rmann-Su for the CSM classes of Schubert cells and some elaborate computer calculations by R. Rimanyi and L. Mihalcea, I conjecture that the CSM classes of the Richardson cells expressed in the Schubert basis have nonnegative coefficients. This conjecture was principally motivated by a new product $\square$ coming from the Segre classes in the cohomology of flag varieties (such that the associated Gr of this product is the standard cup product) and the conjecture that the structure constants of this new product $\square$ in the standard Schubert basis have alternating sign behavior. I prove that this conjecture on the sign of the structure constants of $\square$ would follow from my above positivity conjecture about the CSM classes of Richardson cells.