Causal trees

The intent of the paper is to reconcile two antagonist views on bisimulation semantics for concurrency: the interleaving approach and the approach by partial orders. The so-called causal trees are a variant of Milner's synchronisation trees with enriched action labels which supply indication of the observable causes of observable actions. Concerning CCS, we construct an algebra of causal trees with two byproducts: a complete axiomatization of weak causal bisimulation between finite terms and a fully abstract model of recursive programs.