[X/Fe] vs [Fe/H] for light elements in the SMC adopting different IMFs. Abundance patterns are shown for models adopting a Kroupa et al. (1993) IMF (top panels) and a modified Kroupa et al. (1993) IMF with steeper high-mass end slope (top-light IMF, bottom panels). Solid lines are genuine chemical evolution tracks for models with the re-calibrated SFEs adopted for the particular IMF set-up, while dashed lines are models with the same SFEs used for the reference Kroupa (2001) IMF. Cyan shaded regions are predictions for the model with the re-calibrated SFEs adopted for the IMF set-up, accounting for observational uncertainties ('synthetic model'). Data are as in Fig. 4.