Universality of mod-p cohomology

Let p be an odd prime number. We relate the algebraic notion of a mod-p formal group law and the topological notion of a mod-p oriented ring spectrum. It is shown that there exists a universal mod-p oriented ring spectrum MOp which splits as a wedge sum of Eilenberg-MacLane spectra. The mod-p Eilenberg-MacLane spectrum is shown to be the universal mod-p oriented ring spectrum with an additive mod-p formal group law.     

Homotopy limits of model categories over inverse index categories

In this note we give a model category theoretic interpretation of the homotopy colimit of the diagram of simplicial localizations coming from a diagram of model categories in the case of an inverse indexing category.