Distribution of stars in the true chemical space. Left panel: [C/Fe] vs. [Fe/H]. Right panel: [α/Fe] vs. [Fe/H]. The color represents the predicted class, with blue indicating stars not flagged as enhanced and/or depleted, and pink indicating those flagged as enhanced and/or depleted. The pink-highlighted regions indicate the approximate boundaries for α PMP and CEMP stars, as described in Sect. 2.5, where α PMP stars are defined by [α/Fe]<0.0 and [Fe/H]<−1.0, and CEMP stars by [C/Fe]>0.7 and [Fe/H]<−1.0.