A Semantics to Generate the Context-sensitive Synchronized Control-Flow Graph (extended)

The CSP language allows the specification and verification of complex concurrent systems. Many analyses for CSP exist that have been successfully applied in different industrial projects. However, the cost of the analyses performed is usually very high, and sometimes prohibitive, due to the complexity imposed by the non-deterministic execution order of processes and to the restrictions imposed on this order by synchronizations. In this work, we define a data structure that allows us to statically simplify a specification before the analyses. This simplification can dras- tically reduce the time needed by many CSP analyses. We also introduce an algorithm able to automatically generate this data structure from a CSP specification. The algorithm has been proved correct and its implementation for the CSP's animator ProB is publicly available.Tamarit Muñoz, S.; Silva Galiana, JF.; Llorens Agost, ML.; Oliver Villarroya, FJ. (2010). A Semantics to Generate the Context-sensitive Synchronized Control-Flow Graph (extended). http://hdl.handle.net/10251/839

Analysis Techniques for Concurrent Programming Languages

Los lenguajes concurrentes est an cada d a m as presentes en nuestra sociedad, tanto en las nuevas tecnolog as como en los sistemas utilizados de manera cotidiana. M as a un, dada la actual distribuci on de los sistemas y su arquitectura interna, cabe esperar que este hecho siga siendo una realidad en los pr oximos a~nos. En este contexto, el desarrollo de herramientas de apoyo al desarrollo de programas concurrentes se vuelve esencial. Adem as, el comportamiento de los sistemas concurrentes es especialmente dif cil de analizar, por lo que cualquier herramienta que ayude en esta tarea, a un cuando sea limitada, ser a de gran utilidad. Por ejemplo, podemos encontrar herramientas para la depuraci on, an alisis, comprobaci on, optimizaci on, o simpli caci on de programas. Muchas de ellas son ampliamente utilizadas por los programadores hoy en d a. El prop osito de esta tesis es introducir, a trav es de diferentes lenguajes de programaci on concurrentes, t ecnicas de an alisis que puedan ayudar a mejorar la experiencia del desarrollo y publicaci on de software para modelos concurrentes. En esta tesis se introducen tanto an alisis est aticos (aproximando todas las posibles ejecuciones) como din amicos (considerando una ejecuci on en concreto). Los trabajos aqu propuestos di eren lo su ciente entre s para constituir ideas totalmente independientes, pero manteniendo un nexo com un: el hecho de ser un an alisis para un lenguaje concurrente. Todos los an alisis presentados han sido de nidos formalmente y se ha probado su correcci on, asegurando que los resultados obtenidos tendr an el grado de abilidad necesario en sistemas que lo requieran, como por ejemplo, en sistemas cr ticos. Adem as, se incluye la descripci on de las herramientas software que implementan las diferentes ideas propuestas. Esto le da al trabajo una utilidad m as all a del marco te orico, permitiendo poner en pr actica y probar con ejemplos reales los diferentes an alisis. Todas las ideas aqu presentadas constituyen, por s mismas, propuestas aplicables en multitud de contextos y problemas actuales. Adem as, individualmente sirven de punto de partida para otros an alisis derivados, as como para la adaptaci on a otros lenguajes de la misma familia. Esto le da un valor a~nadido a este trabajo, como bien atestiguan algunos trabajos posteriores que ya se est an bene ciando de los resultados obtenidos en esta tesis.Concurrent languages are increasingly present in our society, both in new technologies and in the systems used on a daily basis. Moreover, given the current systems distribution and their internal architecture, one can expect that this remains so in the coming years. In this context, the development of tools to support the implementation of concurrent programs becomes essential. Futhermore, the behavior of concurrent systems is particularly difficult to analyse, so that any tool that helps in this task, even if in a limited way, will be very useful. For example, one can find tools for debugging, analysis, testing, optimisation, or simplification of programs, which are widely used by programmers nowadays. The purpose of this thesis is to introduce, through various concurrent programming languages, some analysis techniques that can help to improve the experience of the software development and release for concurrent models. This thesis introduces both static (approximating all possible executions) and dynamic (considering a specific execution) analysis. The topics considered here differ enough from each other to be fully independent. Nevertheless, they have a common link: they can be used to analyse properties of a concurrent programming language. All the analyses presented here have been formally defined and their correctness have been proved, ensuring that the results will have the reliability degree which is needed for some systems (for instance, for critical systems). It also includes a description of the software tools that implement the different ideas proposed. This gives the work a usefulness well beyond the theoretical aspect, allowing us to put it in practice and to test the different analyses with real-world examples All the ideas here presented are, by themselves, approaches that can be applied in many current contexts and problems. Moreover, individually they serve as a starting point for other derived analysis, as well as for the adaptation to other languages of the same family. This gives an added value to this work, a fact confirmed by some later works that are already benefiting from the results obtained in this thesis.Tamarit Muñoz, S. (2013). Analysis Techniques for Concurrent Programming Languages [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31651TESI

Graph generation to statically represent CSP processes

The CSP language allows the specification and verification of complex concurrent systems. Many analyses for CSP exist that have been successfully applied in different industrial projects. However, the cost of the analyses performed is usually very high, and sometimes prohibitive, due to the complexity imposed by the non-deterministic execution order of processes and to the restrictions imposed on this order by synchronizations. In this work, we define a data structure that allows us to statically simplify a specification before the analyses. This simplification can drastically reduce the time needed by many CSP analyses. We also introduce an algorithm able to automatically generate this data structure from a CSP specification. The algorithm has been proved correct and its implementation for the CSP's animator ProB is publicly available. © 2011 Springer-Verlag.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovación under grant TIN2008-06622-C03-02, by the Generalitat Valenciana under grant ACOMP/2010/042, and by the Universidad Politécnica de Valencia (Program PAID-06-08). Salvador Tamarit was partially supported by the Spanish MICINN under FPI grant BES-2009-015019.Llorens Agost, ML.; Oliver Villarroya, J.; Silva Galiana, JF.; Tamarit Muñoz, S. (2011). Graph generation to statically represent CSP processes. En Logic-Based Program Synthesis and Transformation. Springer Verlag (Germany). 6564:52-66. https://doi.org/10.1007/978-3-642-20551-4_4S52666564Brassel, B., Hanus, M., Huch, F., Vidal, G.: A Semantics for Tracing Declarative Multi-paradigm Programs. In: Moggi, E., Warren, D.S. (eds.) 6th ACM SIGPLAN Int’l Conf. on Principles and Practice of Declarative Programming (PPDP 2004), pp. 179–190. ACM, New York (2004)Butler, M., Leuschel, M.: Combining CSP and B for specification and property verification. In: Fitzgerald, J., Hayes, I.J., Tarlecki, A. (eds.) FM 2005. LNCS, vol. 3582, pp. 221–236. Springer, Heidelberg (2005)Hoare, C.A.R.: Communicating Sequential Processes. Prentice-Hall, Upper Saddle River (1985)Kavi, K.M., Sheldon, F.T., Shirazi, B., Hurson, A.R.: Reliability Analysis of CSP Specifications using Petri Nets and Markov Processes. In: 28th Annual Hawaii Int’l Conf. on System Sciences (HICSS 1995). Software Technology, vol. 2, pp. 516–524. IEEE Computer Society, Washington, DC, USA (1995)Ladkin, P., Simons, B.: Static Deadlock Analysis for CSP-Type Communications. In: Responsive Computer Systems (Ch. 5). Kluwer Academic Publishers, Dordrecht (1995)Leuschel, M., Butler, M.: ProB: an Automated Analysis Toolset for the B Method. Journal of Software Tools for Technology Transfer 10(2), 185–203 (2008)Leuschel, M., Llorens, M., Oliver, J., Silva, J., Tamarit, S.: Static Slicing of CSP Specifications. In: Hanus, M. (ed.) 18th Int’l Symp. on Logic-Based Program Synthesis and Transformation (LOPSTR 2008), pp. 141–150. Technical report, DSIC-II/09/08, Universidad Politécnica de Valencia (July 2008)Leuschel, M., Llorens, M., Oliver, J., Silva, J., Tamarit, S.: SOC: a Slicer for CSP Specifications. In: Puebla, G., Vidal, G. (eds.) 2009 ACM SIGPLAN Symposium on Partial Evaluation and Semantics-based Program Manipulation (PEPM 2009), pp. 165–168. ACM, New York (2009)Leuschel, M., Llorens, M., Oliver, J., Silva, J., Tamarit, S.: The MEB and CEB static analysis for CSP specifications. In: Hanus, M. (ed.) LOPSTR 2008. LNCS, vol. 5438, pp. 103–118. Springer, Heidelberg (2009)Llorens, M., Oliver, J., Silva, J., Tamarit, S.: A Semantics to Generate the Context-sensitive Synchronized Control-Flow Graph (extended). Technical report DSIC, Universidad Politécnica de Valencia, Valencia, Spain (June 2010), http://www.dsic.upv.es/~jsilvaLlorens, M., Oliver, J., Silva, J., Tamarit, S.: Transforming Communicating Sequential Processes to Petri Nets. In: Topping, B.H.V., Adam, J.M., Pallarés, F.J., Bru, R., Romero, M.L. (eds.) Seventh Int’l Conference on Engineering Computational Technology (ICECT 2010). Civil-Comp Press, Stirlingshire, UK, Paper 26 (2010)Roscoe, A.W., Gardiner, P.H.B., Goldsmith, M., Hulance, J.R., Jackson, D.M., Scattergood, J.B.: Hierarchical Compression for Model-Checking CSP or How to Check 1020 Dining Philosophers for Deadlock. In: Brinksma, E., Cleaveland, R., Larsen, K.G., Margaria, T., Steffen, B. (eds.) TACAS 1995. LNCS, vol. 1019, pp. 133–152. Springer, Heidelberg (1995)Roscoe, A.W.: The Theory and Practice of Concurrency. Prentice Hall, Upper Saddle River (2005

Homogeneous and Scalable Gene Expression Regulatory Networks with Random Layouts of Switching Parameters

We consider a model of large regulatory gene expression networks where the thresholds activating the sigmoidal interactions between genes and the signs of these interactions are shuffled randomly. Such an approach allows for a qualitative understanding of network dynamics in a lack of empirical data concerning the large genomes of living organisms. Local dynamics of network nodes exhibits the multistationarity and oscillations and depends crucially upon the global topology of a "maximal" graph (comprising of all possible interactions between genes in the network). The long time behavior observed in the network defined on the homogeneous "maximal" graphs is featured by the fraction of positive interactions ($0\leq \eta\leq 1$) allowed between genes. There exists a critical value $\eta_c<1$ such that if $\eta<\eta_c$, the oscillations persist in the system, otherwise, when $\eta>\eta_c,$ it tends to a fixed point (which position in the phase space is determined by the initial conditions and the certain layout of switching parameters). In networks defined on the inhomogeneous directed graphs depleted in cycles, no oscillations arise in the system even if the negative interactions in between genes present therein in abundance ($\eta_c=0$). For such networks, the bidirectional edges (if occur) influence on the dynamics essentially. In particular, if a number of edges in the "maximal" graph is bidirectional, oscillations can arise and persist in the system at any low rate of negative interactions between genes ($\eta_c=1$). Local dynamics observed in the inhomogeneous scalable regulatory networks is less sensitive to the choice of initial conditions. The scale free networks demonstrate their high error tolerance.Comment: LaTeX, 30 pages, 20 picture

Robust Temporally Coherent Laplacian Protrusion Segmentation of 3D Articulated Bodies

In motion analysis and understanding it is important to be able to fit a suitable model or structure to the temporal series of observed data, in order to describe motion patterns in a compact way, and to discriminate between them. In an unsupervised context, i.e., no prior model of the moving object(s) is available, such a structure has to be learned from the data in a bottom-up fashion. In recent times, volumetric approaches in which the motion is captured from a number of cameras and a voxel-set representation of the body is built from the camera views, have gained ground due to attractive features such as inherent view-invariance and robustness to occlusions. Automatic, unsupervised segmentation of moving bodies along entire sequences, in a temporally-coherent and robust way, has the potential to provide a means of constructing a bottom-up model of the moving body, and track motion cues that may be later exploited for motion classification. Spectral methods such as locally linear embedding (LLE) can be useful in this context, as they preserve "protrusions", i.e., high-curvature regions of the 3D volume, of articulated shapes, while improving their separation in a lower dimensional space, making them in this way easier to cluster. In this paper we therefore propose a spectral approach to unsupervised and temporally-coherent body-protrusion segmentation along time sequences. Volumetric shapes are clustered in an embedding space, clusters are propagated in time to ensure coherence, and merged or split to accommodate changes in the body's topology. Experiments on both synthetic and real sequences of dense voxel-set data are shown. This supports the ability of the proposed method to cluster body-parts consistently over time in a totally unsupervised fashion, its robustness to sampling density and shape quality, and its potential for bottom-up model constructionComment: 31 pages, 26 figure

Static slicing of explicitly synchronized languages

Static analysis of concurrent languages is a complex task due to the non-deterministic execution of processes. If the concurrent language being studied allows process synchronization, then the analyses are even more complex (and thus expensive), e.g., due to the phenomenon of deadlock. In this work we introduce a static analysis technique based on program slicing for concurrent and explicitly synchronized languages in general, and CSP in particular. Concretely, given a particular point in a specification, our technique allows us to know what parts of the specification must necessarily be executed before this point, and what parts of the specification could be executed before it. Our technique is based on a new data structure that extends the Synchronized Control Flow Graph (SCFG). We show that this new data structure improves the SCFG by taking into account the context in which processes are called and, thus, it makes the slicing process more precise. The technique has been implemented and tested with real specifications, producing good results. After formally defining our technique, we describe our tool, its architecture, its main applications and the results obtained from several experiments conducted in order to measure the performance of the tool. © 2012 Elsevier Inc. All rights reserved.This work has been partially supported by the Spanish Ministerio de Economia y Competitividad (Secretaria de Estado de Investigacion, Desarrollo e Innovacion) under grant TIN2008-06622-C03-02 and by the Generalitat Valenciana under grant PROMETEO/2011/052. Salvador Tamarit was partially supported by the Spanish MICINN under FPI grant BES-2009-015019.Leuschel ., M.; Llorens Agost, ML.; Oliver Villarroya, J.; Silva Galiana, JF.; Tamarit Muñoz, S. (2012). Static slicing of explicitly synchronized languages. Information and Computation. 214:10-46. https://doi.org/10.1016/j.ic.2012.02.005S104621

Toward the Static Detection of Deadlock in Java Software

Concurrency is the source of many real-world software reliability and security problems. Concurrency defects are difficult to detect because they defy conventional software testing techniques due to their non-local and non-deterministic nature. We focus on one important aspect of this problem: static detection of the possibility of deadlock - a situation in which two or more processes are prevented from continuing while each waits for resources to be freed by the continuation of the other. This thesis proposes a flow-insensitive interprocedural static analysis that detects the possibility that a program can deadlock at runtime. Our analysis proceeds in two steps. The first extracts the real call graph decorated with acquired locks from the target program. The second analysis this decorated graph to report how a possible deadlock may occur at runtime. We demonstrate our analysis via a prototype implementation that detects deadlock conditions within two small Java programs. The two principle limitations of our analysis are on the target program: (1) we need its real call graph and (2) its overall size is limited. Construction of the real call graph requires perfect aliasing information. The program\u27s size our technique is able to analyze is roughly 35 kSLOC

Slicing Techniques Applied to Concurrent Languages

In this thesis are presented different program slicing techniques for two concurrent languages: CSP and Petri Nets. As for CSP, two static slices are introduced, using both a new kind of graph. Furthermore, their implementation is also presented and tested. As for Petri Nets, two dynamic slicing techniques are proposed.Tamarit Muñoz, S. (2008). Slicing Techniques Applied to Concurrent Languages. http://hdl.handle.net/10251/13627Archivo delegad