Trend of [Mg/Fe] as a function of [Al/Fe] for the stars analyzed in this study. The blue dots and the green crosses represent the MP and M-int1 stars with [Al/Fe] > 1 dex, respectively. The gray dots represent the entire sample. The error bar in the top-right corner represents the typical measurement error associated with the data. The dashed line indicates the value [Al/Fe] = 1 dex. The distributions of the two subsamples are shown in the right panel with the corresponding colors.