Effective cosmological "constant " and quintessence
  In this paper we present exactly solved extended quintessence models; furthermore, through a dynamical effective Q-cosmological "constant", we recover some of the L decaying cases found in the literature. Finally we introduce a sort of complementarity between the Q-dominated or L-dominated expansions of the Universe. 
R. de Ritis (INFN and Dipartimento di Scienze Fisiche, Universita` di   Napoli), A.A. Marino (Osservatorio Astronomico di Ca...