Evolution of the surface abundance of ³He as a function of stellar luminosity for 1.5 M_⊙ models with Z = 10^-4 and Z_⊙ as indicated. Main evolution steps are pointed out with different symbols.(Left) Standard case computed up to the end of the second dredge-up only. (Right) Models including either thermohaline mixing only (black solid lines), or both thermohaline and rotation-induced mixing (red dashed lines; V_ZAMS/V_crit = 0.45); at Z_⊙ the non-standard models are both computed up to the AGB tip.