On the expressiveness of higher dimensional automata

In this paper I compare the expressive power of several models of concurrency based on their ability to represent causal dependence. To this end, I translate these models, in behaviour preserving ways, into the model of higher dimensional automata (HDA), which is the most expressive model under investigation. In particular, I propose four different translations of Petri nets, corresponding to the four different computational interpretations of nets found in the literature.     

On Improving Backwards Verification of Timed Automata (Extended Abstract)

Verification techniques for Timed Automata [2] built in tools like Kronos [7] are based on the fixpoint calculus of an appropriate operator. In this work, we present different alternatives to calculate that fixpoint, which have direct impact in the number of iterations needed to converge.     

A Language for Verification and Manipulation of Web Documents: (Extended Abstract)

In this paper we develop the language theory underpinning the logical framework PLF. This language features lambda abstraction with patterns and application via pattern-matching. Reductions are allowed in patterns. The framework is particularly suited as a metalanguage for encoding rewriting logics and logical systems where proof terms have a special syntactic constraints, as in term rewriting systems, and rule-based languages. PLF is a conservative extension of the well-known Edinburgh Logical Framework LF. Because of sophisticated pattern matching facilities PLF is suitable for verification and manipulation of HXML documents.     

Completeness and Counter-Example Generations of a Basic Protocol Logic: (Extended Abstract)

We give an axiomatic system in first-order predicate logic with equality for proving security protocols correct. Our axioms and inference rules derive the basic inference rules, which are explicitly or implicitly used in the literature of protocol logics, hence we call our axiomatic system Basic Protocol Logic (or BPL, for short). We give a formal semantics for BPL, and show the completeness theorem such that for any given query (which represents a correctness property) the query is provable iff it is true for any model. Moreover, as a corollary of our completeness proof, the decidability of provability in BPL holds for any given query. In our formal semantics we consider a “trace” any kind of sequence of primitive actions, counter-models (which are generated from an unprovable query) cannot be immediately regarded as realizable traces (i.e., attacked processes on the protocol in question). However, with the aid of Comon-Treinen's algorithm for the intruder deduction problem, we can determine whether there exists a realizable trace among formal counter-models, if any, generated by the proof-search method (used in our completeness proof). We also demonstrate that our method is useful for both proof construction and flaw analysis by using a simple example.     

On Taylor series expansions for waiting times in tandem queues: an algorithm for calculating the coefficients and an investigation of the approximation error

Recently, a Taylor series expansion was developed for expected stationary waiting times in open (max,+)-linear stochastic systems with Poisson input process; these systems cover various instances of queueing networks.As an application, we present an algorithm for calculating the coefficients for infinite capacity tandem queueing networks with discrete service-time distributions. The algorithm works quite efficiently if the random vector of the service times of all servers is concentrated at a small number of atoms. We investigate the relative error of the Taylor approximation by simulation; in many cases, it follows very well a simple expression which holds exactly for independent, exponentially distributed servers.     

On the supervisory control of multi-agent product systems: Controllability properties

Multi-Agent (MA) product systems were defined in [I. Romanovski, P.E. Caines, On the supervisory control of multi-agent products systems, IEEE Trans. Automated Control 51(5) (2006)] where the notion of an MA controllable vector language specification was introduced and necessary and sufficient conditions for the existence of a supervisor for such a specification were derived. In this paper we present a set of results about the controllability of an MA product system and its components. In particular, we obtain an algorithm for finding the infimal MA-controllable superlanguage inf_MA(K) of a given vector (language) specification K w.r.t. an MA product system G and establish that in fact . It is proven that there is an algorithmic procedure for the recursive construction of MA supervisors when additional automata are added to a system via the MA product. Controllability properties of component structures (such as standard controllability and MA controllability of projections) are considered. Several examples are given to illustrate the results of the paper.     

高职《CAD/CAM应用软件(UG)》课程中的学科关联

CAD／CAM应用软件（UG）课程作为机械类专业的一门实践类课程,与其他课程有着紧密的联系。正确认识UG课程中的学科关联,实现和其他专业课程及相关课程设计的纵向贯通,建立科学的、符合工程实际的教学体系,对各专业课的教学起着至关重要的作用。     

Aligning the Qualitative Comparative Analysis (QCA) counterfactual approach with the practice of retroduction: Some preliminary insights

This study offers fresh ontological insights by examining generative causality through the Qualitative Comparative Analysis (QCA) counterfactual lens, in conjunction with Critical Realism and the practice of retroduction. Specifically, it claims that Information Systems (IS) researchers could retroduce generative mechanisms by leveraging the QCA counterfactual approach to causation because retroduction is about conjecturing hypothetical mechanisms that would generate the outcome of interest in a counterfactual fashion. Drawing on an example of typological theorising, this study calls for a renewed effort in the use of retroduction in the study of IS phenomena. In addition, this study sheds new light on the overarching approach for conducting Critical Realist (case study) research. A number of theoretical, methodological, and practical implications are discussed.     

Locating the Eureka Stockade: Use of a geographical information system (GIS) in a historiographical research context

GIS methodology was used for thepurpose of locating the disputed site of ahistorically significant battle, which tookplace in 1854 when miners on an Australian goldfield staged an armed uprising againstgovernment forces. The route of the firstsurvey of the area (1854) and the earliestknown contour map (1856–1857) were overlaid on amodern street grid. Other features such as thevantage points of illustrators and the authorsof eyewitness accounts were also incorporated. The resulting composite map was used as the keyreference framework for comparing andcritically evaluating a large body of primaryand secondary written accounts, and forreaching a conclusion concerning the site.     

On the complex formation of CdCl2 with 1-furoylthioureas: Preconcentration and voltammetric behavior of Cd(II) at carbon paste electrodes modified with 3-monosubstituted and 3,3-disubstituted derivatives

Two series of 1-furoylthioureas were used as modifiers of carbon paste electrodes (CPE). The preconcentration of Cd(II) at CPE modified with these 3-monosubstituted and 3,3-disubstituted 1-furoylthioureas and its subsequent voltammetric determination was studied with Cd(II) test solution. The preconcentration of cadmium at the surface of the modified CPE varied with the steric and electronic nature of the present CS neighboring groups. This is in accord with the changes observed in the Raman spectra of the ligands after complexation with CdCl₂, and with the chemical yields of the complexes obtained.