We characterise the entire set of symmetric stationary Markov-perfect Nash equilibria (MPE) in a differential game of public good investment, using the canonical problem of climate change as an example. We provide a sufficient and necessary condition for MPE and show how the entire set of MPE is...

The following four questions could be asked about each extremalproblem: 1. What are the conditions for an extremum of the problem (necessary, sufficient, necessary andsufficient)? 2. How to describe the evolution of sulutions if the problem is perturbed? 3. Does a solution to the problem exist...