  The theory of stratified institutions is a general axiomatic approach to
model theories where the satisfaction is parameterised by states of the models.
In this paper we further develop this theory by introducing a new technique for
representing stratified institutions which is based on projecting to such
simpler structures. On the one hand this can be used for developing general
results applicable to a wide variety of already existing model theories with
states, such as those based on some form of Kripke semantics. On the other hand
this may serve as a template for defining new such model theories. In this
paper we emphasise on the former application of this technique by developing
general results on model amalgamation and on existence diagrams for stratified
institutions. These are two most useful properties to have in institution
theoretic model theory.

Logic;Logic in Computer Science;Category Theory