diffusion, etc. This effect is shown in Fig.\[fig2\], where we depicted two evolutionary tracks for the mass of 15 $M_\odot$ calculated with and without inward overshooting from the non-burning zone. The blue loop emerges if the $\mu$-gradient left by the evolution during MS is erased by the outer convective zone on the RGB. The range of this convective zone is increased by the inward overshooting. On the other hand, the overshooting from the hydrogen core generally acts against emerging of the blue loops. We show the effect of different values of the overshooting parameter on the evolutionary tracks in the central-left panel ($f=0.01$) and in the bottom-left panel ($f=0.02$) of Fig.\[fig1\]. In both cases the blue loops are present but for the lower value of $f$ they have a larger extension. If we increase the overshooting only from the hydrogen core to $f=0.02$ and we leave $f=0.01$ for the helium core overshooting and the inward overshooting from non-burning zone, the blue loops still emerge but their extension is lower. This is caused mainly by the reduced overshooting from the helium core which decreases the amount of helium available to burn and hence leads to smaller extension of the blue loop.

