Open core and quasi-equilibria with lower semi-continuous preferences

Summary. This note introduces a new concept of core –open core, using which it shows a quasi-equilibrium existence result in an economy where consumers' preference relations are assumed to be lower semi-continuous, but not necessarily to have open lower sections nor to be open valued, such as the lexicographic ordering. As an application, a competitive equilibrium existence result without non-satiation assumption is proved. Received: October 28, 1996; revised version: November 4, 1997