Figure 4. Dependence of the robustness, R, on the degree of coupling, q, for two, interconnected, (a) ER (average degree 〈k〉 = 4) and (b) SF with degree exponent γ = 2.5.

Applying our proposed strategy is applied, the optimal fraction of autonomous nodes is relatively very small. Autonomous nodes are chosen in four different ways: randomly ((blue-) triangles), high degree ((black-)dots), high betweenness ((red-)stars), and high k-shell ((yellow-)rhombi). The insets show the relative improvement of the robustness, for the different strategies of autonomous selection compared with the random case. Results have been averaged over 10² configurations of two networks with 10³ nodes each. For each configuration we averaged over 10³ sequences of random attacks.