Divergence in testing and readiness semantics

Many variants of must-testing semantics have been put forward that are equa lly sensitive to deadlock, but differ for the stress they put on divergence , i.e. on the possibility for systems of getting involved in infinite inter nal computations. Safe-testing is one such variant, that naturally pops up when studying the behavioural pre-congruences induced by certain basic obse rvables. Here, we study the relationship between safe-testing and Olderog's readiness semantics, a semantics induced by a natural process logic. We sh ow that safe-testing is finer than readiness, and coincides with a refineme nt of readiness obtained by tuning Olderog's definition. For both safe-test ing and the original readiness semantics we propose simple complete axiomat izations, which permit a fuller appreciation of their similarities and diff erences. (C) 2001 Elsevier Science B.V. All rights reserved.