Correlations between binary fraction in the core and the physical parameters of clusters. As discussed in the text, we limit the analysis of core binary fractions to clusters with more than 400 stars. The marker color and line color of each panel are indicative of the correlations as shown in the right color bar. The top insets indicate the considered physical parameters, i.e., the x-axis, while the values of the Spearman rank coefficients and p-values are indicated in the bottom inset. Variables μ₀, M_cl, t_rh, Age/t_rh, Age are in logarithm.