1. Division of Computational and Data Sciences Washington University in St. Louis St. Louis Missouri 63130 United States
2. Vermont Complex Systems Center University of Vermont Burlington Vermont 05405 United States
3. Department of Computer Science University of Vermont Burlington Vermont 05405 United States
4. Center On Social Dynamics and Policy Brookings Institution Washington District of Columbia 20036 United States
5. Brown School Washington University in St. Louis St. Louis Missouri 63130 United States
6. Santa Fe Institute Santa Fe New Mexico 87501 United States