A new route to cyclical strategies in two-dimensional optimal control models

This paper proposes a new route to rationalize cyclical policies in concave two-state variable, economic control problems. The essential ingredients are: positive growth; a (positive) externality of the stock; and sluggish control, such that actual control is the sum over historical changes. Given these conditions, it is amazingly simple to generate stable limit cycles, even for separable models. A simple renewable resource model is used to verify this claim.