Slope versus mean value diagram of the frequency ratios in the assumed observable range throughout the main sequence evolution. Top panel: 1.1 M_⊙ models without overshooting (solid red line) and with overshooting (dashed green line). Bottom panel: different mass values for the three considered mixing prescriptions: Ledoux (blue), Schwarzschild (red), and Overshooting (green). A representative 1-σ error bar is plotted at the top left. Models marked with a filled circle have the same value of the large frequency separation, and error bars correspond to 3-σ uncertainties in the frequencies. See text for details.