A Methodological Toolkit to Reform Payment Systems: An Example of Applied Cost-Benefit Analysis

In principle, a careful evaluation of costs and benefits should be a wise rule for everyone who has to take any important decision. In particular, it is very important when a payment system reform is at stake. Since many stakeholders are involved in a payment system reform, the final decisions are going to be the result of several cost-benefit analyses and of “negotiation” among economic agents, in particular system providers, system participants, and end users. In this paper we will only focus on cost-benefit analysis, providing both theoretical guidelines and numerical examples. We conclude that past evaluations of payment system reforms mainly focused on qualitative assessments, hence overlooking quantitative ones. So, we suggest that it would be worthy for international institutions to spend some efforts to build, manage and make available to all countries a database on payments systems, with both relevant data and methods to assess costs and benefits

Approximated Symbolic Computations over Hybrid Automata

Hybrid automata are a natural framework for modeling and analyzing systems which exhibit a mixed discrete continuous behaviour. However, the standard operational semantics defined over such models implicitly assume perfect knowledge of the real systems and infinite precision measurements. Such assumptions are not only unrealistic, but often lead to the construction of misleading models. For these reasons we believe that it is necessary to introduce more flexible semantics able to manage with noise, partial information, and finite precision instruments. In particular, in this paper we integrate in a single framework based on approximated semantics different over and under-approximation techniques for hybrid automata. Our framework allows to both compare, mix, and generalize such techniques obtaining different approximated reachability algorithms.Comment: In Proceedings HAS 2013, arXiv:1308.490

Hybrid Automata and Bisimulations

This paper surveys hybrid automata and bisimulation relations. We formally introduce both notions and briefly present the model checking problem over hybrid automata. We show how, in some cases, bisimulations can be used to quotient infinite state systems to finite ones and, hence, we reduce the model checking over hybrid automata to model checking over finite models. Finally, we review some classes of hybrid automata which admit finite bisimulation quotients

SME Development Banks: Conceptual Framework and Empirical Analysis

In this paper we develop a conceptual framework to define small and medium-sized enterprise development banks (SMEDB). This conceptual effort is motivated by the lack of a clear definition of SMEDB. Once a consistent definition of SMEDB is provided, we compare a sample of banks that are SMEDB according to such definition with a sample of commercial banks. We conclude that it is possible to separate SMEDB from commercial banks in a statistically significant manner by taking into consideration a set of relevant financial indicators and we confirm the widespread idea that SMEDB play a crucial public/social role

Discrete Semantics for Hybrid Automata

Many natural systems exhibit a hybrid behavior characterized by a set of continuous laws which are switched by discrete events. Such behaviors can be described in a very natural way by a class of automata called hybrid automata. Their evolution are represented by both dynamical systems on dense domains and discrete transitions. Once a real system is modeled in a such framework, one may want to analyze it by applying automatic techniques, such as Model Checking or Abstract Interpretation. Unfortunately, the discrete/continuous evolutions not only provide hybrid automata of great flexibility, but they are also at the root of many undecidability phenomena. This paper addresses issues regarding the decidability of the reachability problem for hybrid automata (i.e., "can the system reach a state a from a state b?") by proposing an "inaccurate" semantics. In particular, after observing that dense sets are often abstractions of real world domains, we suggest, especially in the context of biological simulation, to avoid the ability of distinguishing between values whose distance is less than a fixed \u3b5. On the ground of the above considerations, we propose a new semantics for first-order formul\ue6 which guarantees the decidability of reachability. We conclude providing a paradigmatic biological example showing that the new semantics mimics the real world behavior better than the precise one

Is Hyper-extensionality Preservable Under Deletions of Graph Elements?

Any hereditarily finite set S can be represented as a finite pointed graph \u2013dubbed membership graph\u2013 whose nodes denote elements of the transitive closure of {S} and whose edges model the membership relation. Membership graphs must be hyper-extensional, that is pairwise distinct nodes are not bisimilar and (uniquely) represent hereditarily finite sets. We will see that the removal of even a single node or edge from a membership graph can cause \u201ccollapses\u201d of different nodes and, therefore, the loss of hyper-extensionality of the graph itself. With the intent of gaining a deeper understanding on the class of hyper-extensional hereditarily finite sets, this paper investigates whether pointed hyper-extensional graphs always contain either a node or an edge whose removal does not disrupt the hyper-extensionality property

Unwinding biological systems

Unwinding conditions have been fruitfully exploited in Information Flow Security to define persistent security properties. In this paper we investigate their meaning and possible uses in the analysis of biological systems. In particular, we elaborate on the notion of robustness and propose some instances of unwinding over the process algebra Bio-PEPA and over hybrid automata. We exploit such instances to analyse two case-studies: Neurospora crassa circadian system and Influenza kinetics models

An information-oriented paradigm in evaluating accuracy and agreement in radiology

The goal of any radiological diagnostic process is to gain information about the patient's status. However, the mathematical notion of information is usually not adopted to measure the performance of a diagnostic test or the agreement among readers in providing a certain diagnosis. Indeed, commonly used metrics for assessing diagnostic accuracy (e.g., sensitivity and specificity) or inter-reader agreement (Cohen [Formula: see text] statistics) use confusion matrices containing the number of true- and false positives/negatives results of a test, or the number of concordant/discordant categorizations, respectively, thus lacking proper information content. We present a methodological paradigm, based on Shannon's information theory, aiming to measure both accuracy and agreement in diagnostic radiology. This approach models the information flow as a "diagnostic channel" connecting the state of the patient's disease and the radiologist or, in the case of agreement analysis, as an "agreement channel" linking two or more radiologists evaluating the same set of images. For both cases, we proposed some measures, derived from Shannon's mutual information, which can represent an alternative way to express diagnostic accuracy and agreement in radiology.Key points• Diagnostic processes can be modeled with information theory (IT).• IT metrics of diagnostic accuracy are independent from disease prevalence.• IT metrics of inter-reader agreements can overcome Cohen κ pitfalls