[α/Fe] vs. [Fe/H] for stars in the sample of Adibekyan et al. (2012). α is defined as the mean of the abundances of magnesium, silicon and titanium. The thick and thin disk sequences are distinguished by whether they lie above or below the three segments of the solid line respectively. The two double circles at [Fe/H] < −1.0 dex and [α/Fe] < 0.1 dex are HIP 74234 and HIP 100568, while the two solid dot-and-circle symbols represent HIP 54641 and HIP 57360 (see text).