In the standard testing theory of DeNicola-Hennessy one process is considered to be a refinement of another if every test guaranteed by the former is also guaranteed by the latter. In the domain of web services this has been recast, with processes viewed as servers and tests as clients. In this way the standard refinement preorder between servers is determined by their ability to satisfy client...

Stuttering bisimulation is a well-known behavioural equivalence that preserves CTL-X, namely CTL without the next-time operator X. Correspondingly, the stuttering simulation preorder induces a coarser behavioural equivalence that preserves the existential fragment ECTL-{X,G}, namely ECTL without the next-time X and globally G operators. While stuttering bisimulation equivalence can be computed ...

We present a new stackless ray traversal algorithm which makes use of kD-tree augmented with sparsely distributed bounding boxes. The proposed traversal algorithm is not restricted to start the hierarchy traversal at the root node and so it can exploit the knowledge of the ray origin. The algorithm achieves traversal times comparable with the traditional hierarchical traversal as well as recent...

This paper introduces a novel (bi)simulation{based faster{than preorder which relates asynchronous processes with respect to their worst{case timing behavior. The studies are conducted for a conservative extension of the process algebra CCS, called TACS, which permits the speci cation of maximal time bounds of actions. TACS complements work in plain process algebras which compares asynchronous ...

We define (bi)simulations up-to a preorder and show how we can use them to provide a coinductive, (bi)simulation-like, characterisation of semantic (equivalences) preorders for processes. In particular, we can apply our results to all the semantics in the linear time-branching time spectrum that are defined by preorders coarser than the ready simulation preorder. The relation between bisimulati...

An intensional model for the programming language PCF is described, in which the types of PCF are interpreted by games, and the terms by certain “history-free” strategies. This model is shown to capture definability in PCF. More precisely, every compact strategy in the model is definable in a certain simple extension of PCF. We then introduce an intrinsic preorder on strategies, and show that i...

In this paper we define simulations up-to a preorder and show how we can use them to provide a coinductive, simulation-like, characterization of semantic preorders for processes. The result applies to a wide class of preorders, in particular to all semantic preorders coarser than the ready simulation preorder in the linear time-branching time spectrum. An interesting but unexpected result is th...