Figure 5

Single and tangent spherical shells: cost function and viability condition. The top-left and bottom-left panels show the cost function for a single and two tangent spherical shells, respectively, in a two-dimensional parameter space. The top-right and bottom-right panels show the contour plots that correspond to the left-side panels. In both cases, the viability condition is fulfilled by all the points enclosed by the two curves for which the value of the cost function is 0.1.