ion-side and Display-side behaviours of an interactor. Interactors are characterised by the behaviour they exhibit when observed from the abstraction or the display sides. The abstraction-side behaviour of the interactor is observed by interaction at gates Gaout and Gainp. The display-side behaviour is observed at gates Gdinp and Gdout. They are described by the pseudo-LOTOS expressions: A P = ...

The main result of the paper is a constructive proof of the following equivalence: two pure -terms are observationally equivalent in the lazy concurrent -calculus i they have the same L evy-Longo trees. An algorithmwhich allows to build a context discriminating any two pure -terms with di erent L evy-Longo trees is described. It follows that contextual equivalence coincides with behavioural equ...

Abstract : Let be a 2nd order ODE. By Cartan equivalence method, we will study the local equivalence problem under the transformations group of time-fixed coordinates. We are going to solve this problem by an applicable method which has been recognized by R. Gardner, and classify them.   

We present an elementary algorithm for deciding bisimulation equivalence between arbitrary context-free processes. This improves on the state of the art algorithm of Christensen, H uttel and Stirling consisting of two semi-decision procedures running in parallel, which prohibits any complexity estimation. The point of our algorithm is the eeective construction of a nite relation characterizing ...