Comparison of abundance ratios, [X/Fe], and metallicity, [Fe/H], as a function of galactocentric distance for the bulge of M31 (solid lines) with predictions from our chemical evolution models (dashed lines). The left and middle panels show models for a variable IMF scenario, adopting stellar yields from R10 and F04, respectively. The right panel shows models for an outside-in quenching scenario, with stellar yields from F04. All models are computed for the center and for two additional regions at radii of 300 and 600 pc (empty squares, crosses, and empty triangles in the left, middle, and right panels, respectively). Different elemental abundances and [Fe/H] are plotted in various colors (see labels in the rightmost panel). Error bars on observed data points are shown only for the innermost and outermost bins, as in Fig. 4. We corrected oxygen abundances for the Milky Way pattern, as detailed in Sect. 6.2.