Flat and weakly flat projection algebras. (Q1771962)

The concept of a projection algebra was introduced by \textit{H.\ Ehrig} and his collaborators as an algebraic version of ultrametric spaces. This concept is useful in computer science as a convenient tool for algebraic specification of process algebras. By \(\mathcal{PRO}\) is denoted the category of projection algebras. \(A \in \mathcal{PRO}\) is flat if the functor \(A \otimes - : \mathcal{PRO} \rightarrow \mathcal{S}et\) preserves finite limits. The authors characterize flat and weakly flat projection algebras.