[C/N] (upper panel) and [C/O] (lower panel) versus metallicity. Black symbols correspond to the yields of our computed models. The cases in which dilution has been taken into account are represented in grey. They should be located at the same [Fe/H] as the non-diluted yields, but we displaced them –0.1 dex for the sake of clarity. For comparison, observational data of EMP (black solid circles) and CEMP (red open circles) from the SAGA database are represented in both panels.