Weak Bisimulation Up to Elaboration

We study the use of the elaboration preorder (due to ArunKumar and Natarajan) in the framework of up-to techniques for weak bisimulation. We show that elaboration yields a correct technique that encompasses the commonly used up to expansion technique. We also define a theory of up-to techniques for elaboration that in particular validates an elaboration up to elaboration technique, while it is known that weak bisimulation up to weak bisimilarity is unsound. In this sense, the resulting setting improves over previous works in terms of modularity. Our results are obtained using nontrivial proofs that exploit termination arguments. In particular, we need the termination of internal computations for the up-to techniques to be correct. We show how this condition can be relaxed to some extent in order to handle processes exhibiting infinite internal behaviour.