Positivity of Schur function expansions of Thom polynomials

Combining the approach to Thom polynomials via classifying spaces of singularities with the Fulton-Lazarsfeld theory of cone classes and positive polynomials for ample vector bundles, we show that the coefcients of the Schur function expansions of the Thom polynomials of stable singularities are nonnegative with positive sum.