Fig. 6. Sustainability diagrams of model 3-5 with competition a and investment ε depending upon price p through the formulas and . The darkest regions correspond to sustainable policies that are both risky for the economy and for the environment. In (a) the component ã is on the vertical axis. In (b) ε=0.6. In (c) ã =2. In (d) a=6. All other parameters are as in Figure 2b.