A note on the coincidence between Stackelberg and Nash equilibria in a differential game between government and firms

[cat] A Navas i Marín Solano es va demostrar la coincidència entre els equilibris de Nash i de Stackelberg per a una versi´o modificada del joc diferencial proposat por Lancaster (1973). Amb l’objectiu d’obtenir una solució interior, es van imposar restriccions importants sobre el valors dels paràmetres del model. En aquest treball estenem aquest resultat, en el límit en que la taxa de descompte és igual a zero, eliminant les restriccions i considerant totes les solucions possibles.

[eng] In Navas and Marín-Solano (2008) the coincidence between Nash and Stackelberg equilibria for a modified version of the differential game model first proposed by Lancaster (1973) was proved. However, important restrictions on the value of the parameters of the model were included, in order to obtain an interior solution. In this paper we extend the previous result, in the limit when the discount rate is equal to zero, by eliminating the restrictions and taking into account corner solutions.