Fuzzy Bigraphs: An Exercise in Fuzzy Communicating Agents

Bigraphs and their algebra is a model of concurrency. Fuzzy bigraphs are a generalization of birgraphs intended to be a model of concurrency that incorporates vagueness. More specifically, this model assumes that agents are similar, communication is not perfect, and, in general, everything is or happens to some degree.Comment: 11 pages, 3 figure

The turtles of the Purbeck Limestone Group of Dorset, southern England

The turtles from the Purbeck Limestone are revised and it is concluded that there are four shell-based cryptodire species present, namely Pleurosternon bullockii, ‘Glyptops’typocardium comb. nov., Helochelydra anglica comb. nov.,Hylaeochelys latiscutata. There is also one skull-based species, Dorsetochelys delairi, which may prove to be the skull of ‘Glyptops’, Hylaeochelys or an unknown shell-type. All other taxa are junior synonyms except ‘Chelone’obovata Owen, 1842 and Tretosternon punctatum Owen, 1842 which are nomina dubia, the material being unfigured and either lost or incorrectly associated. Other taxonomic conclusions are that (1) because Tretosternon is a nomen dubium, the next senior name for this Purbeck–Wealden genus is Helochelydra Nopcsa, 1928; (2) ‘Pleurosternon’typocardium and ‘Glyptops’ruetimeyeri are synonymous, the senior combination being ‘Glyptops’typocardium; (3) the Purbeck ‘Tretosternon’ material is combined with the holotype and only specimen of Platychelys? anglica as Helochelydra anglica comb. nov.; (4) Hylaeochelys emarginata and H. sollasi are junior synonyms of Hylaeochelys latiscutata; (5) one of Owen's ‘lost’ syntypes of ‘Tretosternon punctatum’ has been recognised and is a plastron of Hylaeochelys latiscutata

Causality and replication in concurrent processes

The replication operator was introduced by Milner for obtaining a simplified description of recursive processes. The standard interleaving semantics denotes the replication of a process P, written !P, a shorthand for its unbound parallel composition, operationally equivalent to the process P | P | …, with P repeated as many times as needed. Albeit the replication mechanism has become increasingly popular, investigations on its causal semantics has been scarce. In fact, the correspondence between replication and unbound parallelism makes it difficult to recover basic properties usually associated with these semantics, such as the so-called concurrency diamond. In this paper we consider the interleaving semantics for the operator proposed by Sangiorgi and Walker, and we show how to refine it in order to capture causality. Furthermore, we prove it coincident with the standard causal semantics for recursive process studied in the literature, for processes defined by means of constant invocations

Measurement of the Difference in R=σ_L/σ_T and of σ^A/σ^D in Deep-Inelastic e-D, e-Fe, and e-Au Scattering

We measured the differences in R=σ_L/σ_T and the cross-section ratio σA/σD in deep-inelastic electron scattering from D, Fe, and Au nuclei in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤5 (Gev/c)^2. Our results for R^A-R^D are consistent with zero for all x and Q^2, indicating that possible contributions to R from nuclear higher-twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The European Muon Collaboration effect is reconfirmed, and the low-x data from all recent experiments, at all Q^2, are now in agreement

Measurement of kinematic and nuclear dependence of R = σ_L/σ_T in deep inelastic electron scattering

We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement

Science for Global Ubiquitous Computing

This paper describes an initiative to provide theories that can underlie the development of the Global Ubiquitous Computer, the network of ubiquitous computing devices that will pervade the civilised world in the course of the next few decades. We define the goals of the initiative and the criteria for judging whether they are achieved; we then propose a strategy for the exercise. It must combine a bottom-up development of theories in directions that are currently pursued with success, together with a top-down approach in the form of collaborative projects relating these theories to engineered systems that exist or are imminent