[1] Med Univ Vienna, Sect Sci Complex Syst, A-1090 Vienna, Austria
[2] Santa Fe Inst, Santa Fe, NM 87501 USA
[3] IIASA, A-2361 Laxenburg, Austria
[4] Univ Oxford, Oxford Martin Sch, Inst New Econ Thinking, Oxford OX1 3LB, England
[5] Univ Oxford, Math Inst, Oxford OX1 3LB, England
[6] Yale Univ, Dept Econ, New Haven, CT 06520 USA