Mathematics Subject Classification (2010): 9lB62, 49145. 4902
Abstract. In the last 5 years. there has been extensive work on the existence and
characterization of solutions of undiscounted optimal programs in simple discrete-
time models of the ‘choice of technique’ in development planning and of lumber
extraction in the economics of forestry. In this expository essay. we present a uni-
fied treatment of the characterization results in two of these models. Furthermore.
with an eye towards extensions to the discounted setting. we present the general
theory, both with or without “smoothness hypotheses" on the felicity function. and
in continuous-time and discrete-time taking special care to distinguish asymptotic
convergence of optimal programs from their classical turnpike properties. We show
* A preliminary version of this work was presented at the Workshop on Mathe-
matical Economics held in Keio University, Tokyo during November l3—l5, 2009.
The authors are grateful to Professor Toru Maruyama for his invitation, and to him
and Professors Alexander Ioffe. Alejandro Jofre, Boris Mordukhovich and Haru
Takahashi for discussion and encouragement. Adriana Piazza gratefully acknowl-
edges the financial support of Programa Basal PFB 03. Centre dc Modeiamiemo
Maremdfico (CMM), Universidad de Chile and that of FONDECYT under project
11090254. Ali Khan would like to acknowledge, in addition, the hospitality of the De-
partamento de Matematica, Universidnd Técnica Federico Santa Maria, of the CMM
and Facuimd de Econrmifn y Negocios at the Universidad dc Chile during his visit in
July 2010. when the final version of this work was completed.