Title:  A categorification of the Stanley symmetric chromatic polynomial

Abstract:  Given a graph G with n vertices, Stanley defined a symmetric polynomial X_G(x_1, x_2, ...) so that for every positive integer k, X_G(1,..,1,0,...) = chi_G(k) is the number of proper k-colourings of G. We build a double chain complex C_*(G) of S_n-modules so that the Frobenius series Frob_G(x;q,t) of the resulting bi-graded homology H_*(G) satisfies Frob_G(x;1,1) = X_G(x_1, x_2, ...).