No abstract

The goal of multi-winner elections is to choose a fixed-size committee based on voters’ preferences. An important concern in this setting is representation: large groups of voters with cohesive preferences should be adequately represented by the election winners. Recently, Aziz et al. proposed two axioms that aim to capture this idea: justified representation (JR) and its strengthening extended justified representation (EJR). In this paper, we extend the work of Aziz et al. in several directions. First, we answer an open question of Aziz et al., by showing that Reweighted Approval Voting satisfies JR for k = 3; 4; 5, but fails it for k >= 6. Second, we observe that EJR is incompatible with the Perfect Representation criterion, which is important for many applications of multi-winner voting, and propose a relaxation of EJR, which we call Proportional Justified Representation (PJR). PJR is more demanding than JR, but, unlike EJR, it is compatible with perfect representation, and a committee that provides PJR can be computed in polynomial time if the committee size divides the number of voters. Moreover, just like EJR, PJR can be used to characterize the classic PAV rule in the class of weighted PAV rules. On the other hand, we show that EJR provides stronger guarantees with respect to average voter satisfaction than PJR does.

Abstract. Web services are a very appropriate communication mechanism to perform distributed business processes among several organisations. These processes should be reliable, because a failure in them can cause high economic losses. To increase their reliability at design time, we have developed VERBUS, a framework for the formal verification of business processes. VERBUS can automatically translate business process definitions to specifications verifiable in several available tools. It is based on a modular and extensible architecture: new process definition languages and verification tools can be added easily to the framework. The prototype of VERBUS presented in this work can verify BPEL4WS process specifications, by translating them to Promela. The Promela specifications are verified with the well known model checker Spin. In this paper we describe the general architecture of VERBUS and how BPEL4WS specifications are translated and verified. The explanation is completed by describing what types of properties can be verified and providing an overview of the implementation.

No abstract

In the current Information Society, being informed is a basic necessity. As one of the main news bussiness actors, news agencies are required to provide fresh, relevant, high-quality information to their customers. Dealing with this requirement is not an easy task, but, as partners of the NEWS (News Engine Web Services) project, we believe that the usage of Semantic Web technologies could help news agencies in achieving that objective. In this paper we will describe the aims and main achievements of the NEWS project, that was just completed. The NEWS Consortium is composed of news agencies Agencia EFE S.A.

The information systems of smart cities offer project developers, institutions, industry and experts the possibility to handle massive incoming data from diverse information sources in order to produce new information services for citizens. Much of this information has to be processed as it arrives because a real-time response is often needed. Stream processing architectures solve this kind of problems, but sometimes it is not easy to benchmark the load capacity or the efficiency of a proposed architecture. This work presents a real case project in which an infrastructure was needed for gathering information from drivers in a big city, analyzing that information and sending real-time recommendations to improve driving efficiency and safety on roads. The challenge was to support the real-time recommendation ser-vice in a city with thousands of simultaneous drivers at the lowest possible cost. In addition, in order to estimate the ability of an infrastructure to handle load, a simulator that emulates the data produced by a given amount of simultaneous drivers was also developed. Experiments with the simulator show how recent stream processing platforms like Apache Kafka could replace custom-made streaming servers in a smart city to achieve a higher scalability and faster responses, together with cost reduction.

No abstract

Although technology for automatic grading of multiple choice exams has existed for several decades, it is not yet as widely available or affordable as it should be. The main reasons preventing this adoption are the cost and the complexity of the set-up procedures. In this article, Eyegrade, a system for automatic grading of multiple choice exams is presented. Whilst most current solutions are based on expensive scanners, Eyegrade offers a truly low-cost solution requiring only a regular off-the-shelf webcam. Additionally, Eyegrade performs both mark recognition as well as optical character recognition (OCR) of hand-written student identification numbers, which avoids the use of bubbles in the answer sheet. When compared to similar webcam-based systems, the user interface in Eyegrade has been designed to provide a more efficient and error-free data collection procedure. The tool has been validated with a set of experiments that show the ease of use (both set-up and operation), the reduction in grading time, and an increase in the reliability of the results when compared with conventional, more expensive systems.