Kinematical Properties of Generalized Inflation

The kinematical properties of Robertson-Walker models which allow a solution of the cosmological horizon and flatness problems are studied: these are called models of generalized inflation. A useful illustration of such inflation is considered in which the background equation of state assumes the form p/ρ = const. < - 1/3. In this context we also discuss a possible solution of the Ω-problem. The general properties of the spectrum of tensor and scalar perturbations generated during the inflationary phase are analyzed. Finally we discuss some examples of generalized inflation which occur mainly in the frame of some recently proposed models of Kaluza-Klein cosmology.