Fig. 11: Interactive effects between oxides as revealed by the SHAP analysis.

Variations on the marginal contribution of (a) CaO and (b) Al2O3 to VHT response under the influence of the total content of alkaline oxides (Na2O + K2O + Li2O). Here, the arrows are added to highlight the dual effects of these two oxides, and the feature values are based on the actual scale. To assist comparison, the vertical and horizontal dash lines indicate the mean feature value and zero marginal contribution, respectively.