On the different notions of arbitrage and existence of equilibrium

In this paper we first prove an equilibrium existence theorem for finite di mensional economies with unbounded below consumption sets. We only assume t hat the individually rational utility set is compact and use the demand app roach instead of the standard Negishi's approach. We next compare the diffe rent concepts of no-arbitrage that have been used in the literature and giv e conditions ibr equivalence between absence of arbitrage and existence of equilibrium Lastly, we introduce the concept of strong unbounded arbitrage and show that the absence of strong unbounded arbitrage implies the compact ness of the individually rational utility set. Journal of Economic Literatu re Classification Numbers: C62, D50. (C) 1999 Academic Press.