Anovel,scalable,on-the-flymodel-checkingprocedureispre- sented to verify bounded PCTL properties of selected individuals in the context of very large systems of independent interacting objects. The proposed procedure combines on-the-fly model checking techniques with deterministic mean-field approximation in discrete time. The asymptotic correctness of the procedure is shown and some results of the applica- tion of a prototype implementation of the FlyFast model-checker are pre- sented
We provide two interpretations, over nondeterministic and probabilistic processes, of PML, the probabilistic version of Hennessy-Milner logic used by Larsen and Skou to characterize bisimilarity of probabilistic processes without internal nondeterminism. We also exhibit two new bisimulation-based equivalences, which are in full agreement with the two different interpretations of PML. The new equivalences are coarser than the bisimilarity for nondeterministic and probabilistic processes proposed by Segala and Lynch, which instead is in agreement with a version of Hennessy-Milner logic extended with an additional probabilistic operator interpreted over state distributions rather than over individual states. The modal logic characterizations provided for the new equivalences thus offer a uniform framework for reasoning on purely nondeterministic processes, reactive probabilistic processes, and nondeterministic and probabilistic processes
Corruption frequently occurs in many aspects of multi-party interaction between private agencies and government employees. Past works studying corruption in a lab context have explicitly included covert or illegal activities in participants’ strategy space or have relied on surveys like the Corruption Perception Index (CPI). This paper studies corruption in ecologically realistic settings in which corruption is not suggested to the players a priori but evolves during repeated interaction. We ran studies involving hundreds of subjects in three countries: China, Israel, and the United States. Subjects interacted using a four-player board game in which three bidders compete to win contracts by submitting bids in repeated auctions, and a single auctioneer determines the winner of each auction. The winning bid was paid to an external “government” entity, and was not distributed among the players. The game logs were analyzed posthoc for cases in which the auctioneer was bribed to choose a bidder who did not submit the highest bid. We found that although China exhibited the highest corruption level of the three countries, there were surprisingly more cases of corruption in the U.S. than in Israel, despite the higher PCI in Israel as compared to the U.S. We also found that bribes in the U.S. were at times excessively high, resulting in bribing players not being able to complete their winning contracts. We were able to predict the occurrence of corruption in the game using machine learning. The significance of this work is in providing a novel paradigm for investigating covert activities in the lab without priming subjects, and it represents a first step in the design of intelligent agents for detecting and reducing corruption activities in such settings.
The availability of massive network and mobility data from diverse domains has fostered the analysis of human behavior and interactions. This data availability leads to challenges in the knowledge discovery community. Several different analyses have been performed on the traces of human trajectories, such as understanding the real borders of human mobility or mining social interactions derived from mobility and viceversa. However, the data quality of the digital traces of human mobility has a dramatic impact over the knowledge that it is possible to mine, and this issue has not been thoroughly tackled in literature so far. In this chapter, we mine and analyze with complex network techniques a large dataset of human trajectories, a GPS dataset from more than 150 k vehicles in Italy. We build a multiresolution spatial grid and we map the trajectories to several complex networks, by connecting the different areas of our region of interest. We also analyze different temporal slices of the network, obtaining a dynamic perspective over its evolution. We analyze the structural properties of the temporal and geographical slices and their human mobility predictive power. The result is a significant advancement in our understanding of the data transformation process that is needed to connect mobility with social network analysis and mining.
This work deals with the numerical simulation and material flow visualization of Friction Stir Welding (FSW) processes. The fourth order Runge- Kutta (RK4) integration method is used for the computation of particle trajectories. The particle tracing method is used to study the effect of input process parameters and pin shapes on the weld quality. The results show that the proposed method is suitable for the optimization of the FSW process.
Agile software development is now in its teens. It began by performing in relatively small pioneering organizations; then it gained the interest of medium-size companies, academia, and applied research institutions and laboratories; nowadays it runs in organizations of any kind, including major software and systems development companies.\ud\udBecause of such a wide diffusion of Agile in industry, the need for collaboration between academics and practitioners increases, in the aim of improving the body of knowledge available to help managers, system engineers, and software engineers to take their managerial/economical, and architectural/project / technical decisions. \ud\udDuring its 15 editions, the XP conference has been a major supporter of the Agile vision of software development. Year after year, the XP conference has been supporting the improvements, observing the growth, of the Agile software development and providing evidence about the advantages that Agile development can provide. In fact, these XP editions brought together industrial practitioners and researchers in the fields of information systems and software development. They examined latest theory, practical applications and implications of agile and lean methods.\udXP2014, in continuity with the past editions, built a multidisciplinary platform for research and practice on various aspects of agile methods, increased interaction and collaboration between practitioners and researchers, discussed and rethought the relationships, synergies, compatibilities and incompatibilities between agile and lean practices.\ud\udXP2014 committees included the Research Program Committee and the Experience Report Program Committee. This book presents the regular papers and short papers that the former, and the experience reports that the latter, respectively, accepted for presentation at XP2014. Let’s note that the acceptance process was really selective; specifically, more than 50% of the submitted papers and experience reports were rejected.\ud\udThis book presents chapters concerning or rethinking Agile and Lean development research topics, including: Contracting, Maturity modeling, Value-Based Software Development, Large-Scale Software Development, Methods, Metrics, Testing, Challenges and Perspectives, Software Development in Practice and Teaching at University. The experience reports come from both industry and research institutes, and their topics span from studying global architecture design approaches to investigating challenges involved when advancing software development practices.\ud\udHopefully, we reached the goal of doing our best in serving the Agile community by synthesizing the states of the art and practice and tracing its perspectives
Parallel computation requires splitting a job among a set of processing units called workers. The computation is generally performed by a set of one or more master workers that split the workload into chunks and distribute them to a set of slave workers. In this setting, communication among workers can be problematic and/or time consuming. Tree search algorithms are particularly suited for being applied in a parallel fashion, as different nodes can be processed by different workers in parallel. In this paper we propose a simple mechanism to convert a sequential tree-search code into a parallel one. In the new paradigm, called SelfSplit, each worker is able to autonomously determine, without any communication with the other workers, the job parts it has to process. Computational results are reported, showing that SelfSplit can achieve an almost linear speedup for hard Constraint Programming applications, even when 64 workers are considered.