[This paper amends the Aumann and Kurz single commodity "Power and Taxes" model in several ways: A linear production technology is assumed, incentive effects are introduced, and tax schedules are restricted to be linear. A theorem is stated which characterizes the linear tax schedules which are the NTU solutions of the model. The solutions of an example are computed, providing a perspective on a result of the Aumann and Kurz model that equilibrium marginal tax rates are not less than 50 per cent. For this example, equilibrium marginal tax rates are less than 50 per cent; incentive effects appear to be responsible for the low tax rates.]

How feasible is violence early-warning prediction? Colombia and Indonesia have unusually fine-grained data. We assemble two decades of local violent events alongside hundreds of annual risk factors. We attempt to predict violence one year ahead with a range of machine learning techniques. Our models reliably identify persistent, high-violence hot spots. Violence is not simply autoregressive, as detailed histories of disaggregated violence perform best, but socioeconomic data substitute well for these histories. Even with unusually rich data, however, our models poorly predict new outbreaks or escalations of violence. These “best-case” scenarios with annual data fall short of workable early-warning systems.