In this paper, we show that bisimulation equivalence between concurrent systems of the type described in [9] is undecidable for two logics --- Linear Temporal Logic LTL and LTL without the nexttime operator. Such concurrent systems contain a control process and arbitrarily many identical user processes. These negative results indicate that it might be difficult to compare two such concurrent systems and obtain the advantages from equivalences that are possible in other simpler models of concurrency [3, 6, 1, 7]. 1 Introduction Most formal models for concurrent systems (referred to as CS subsequently) provide a means for describing, and ultimately, detecting such phenomenon as deadlock, starvation and liveness in such systems. In a resource--oriented model [2, 11], processes are entities executing operations which request and release resources. These resources are controlled by finite state devices called synchronizers. In this model, properties such as deadlock and liveness can be e...

In learning their native language, children develop a remarkable set of capabilities. They acquire knowledge and skills that enable them to produce and comprehend an indefinite number of novel utterances, and to make quite subtle judgments about certain of their properties. The major goal

the morphology and the neural circuitry of these creatures. This genetic language defines a hyperspace containing an indefinite number of possible creatures with behaviors, and when it is searched using optimization techniques, a variety of successful and interesting locomotion strategies emerge, some of which

Ó The Author(s) 2009. This article is published with open access at Springerlink.com Abstract There is little consensus about the characteristics and number of body representations in the brain. In the present paper, we examine the main problems that are encountered when trying to dissociate

Every even indefinite binary form occurs as the Picard lattice of some K3-surface. For these there is an explicit description for the group of isometries, or automorphs as they are called in classical literature [4, 8]. This group is always infinite, while the automorphism group

This paper explores the link between number marking and (in)definiteness in nominals and their interpretation. Differences between bare singulars and plurals in languages without determiners are explained by treating bare nominals as kind terms. Differences arise, it is argued, because singular

. They may also be used to invoke programs. The database can be distributed across an indefinite number of file servers and be as large as available disk space permits. Independently developed KMS databases can be linked together. The KMS user interface uses an extreme form of direct manipulation. A single

Like many other languages, Mandarin Chinese has noun phrases consisting of just a BARE NOUN without any functional elements such as determiners, classifiers, or number morphemes:1

Iterative methods for linear systems of algebraic equations arising from the finite element discretization of nonsymmetric and indefinite elliptic problems are considered. Methods previously known to work well for positive definite, symmetric problems are extended to certain nonsymmetric problems

is the number of samples. We present two algorithms, one being of optimal order, the other up to logarithmic factors. We also prove lower bounds and discuss the dependence of the constants in the error estimates on the dimension. 1