Modelling Concurrent Behaviours by Commutativity and Weak Causality Relations*

Complexc oncurrent behaviours that cannot be handled by causal partial orders are frequently modelled by a relational structures (X,<,衇), where X is a set (of event occurrences), < is causality and 衇 is weak causality relation ([5][9][7][13] and others). It was shown in [7] that the complex case require the pair of relations <> and 衇, where <> is commutativity, however no axioms for the pair <>, 衇 were given. We present such axioms under the assumption that observations of concurrent behaviours are modelled by stratified partial orders (step-sequences).