A precongruence format for should testing preorder

Should testing preorder was proposed as a liveness-preserving precongruence for a process algebra except for nondeterministic choice operator [22]. However, this precongruce result cannot be generalized to other languages before carefully proved. In this paper, we show that τDes format is a precongruence format for should testing preorder. A precongruence format guarantees the precongruence of given preorder by imposing syntactic restrictions on languages. The τDes format [24] was suggested to be a precongruence format for testing preorder, which is incomparable with should testing preorder on discriminative power. Also, we look into its applications on ACP language.