Fig. 6

Global search: (a) current simplex. The predictions obtained using models F(x) and L(x) are juxtaposed against f(x) and l(x) at x_tmp obtained by (10). Here, x_tmp will be accepted as it improves U_L and ||f(x) – f_t||; (b) corresponding simplex update (illustrated assuming that x_tmp is better than x⁽¹⁾ but inferior to x⁽⁰⁾); (c) simplex reduction if x_tmp was rejected.