On a Uniform Turnpike of the Third Kind in the Robinson-Solow-Srinivasan Model

On using McKenzie's taxonomy of optimal accumulation in the long-run, we report a ``uniform turnpike' theorem of the third kind in a model original to Robinson, Solow and Srinivasan (RSS), and further studied by Stiglitz. Our results are presented in the undiscounted, discrete-time setting emphasized in the recent work of Khan-Mitra, and they rely on the importance of either a strictly concave felicity function, or on the value of a ``marginal rate of transformation', ξσ, from one period to the next not being unity. We argue that our results, when viewed through the lens of turnpike theory, have a broader relevance to intertemporal optimization theory, as developed in economics by Ramsey, von Neumann and their followers.