114,857 research outputs found
Extension of Petri Nets by Aspects to Apply the Model Driven Architecture Approach
Within MDA models are usually created in the UML. However, one may prefer to\ud
use different notations such as Petri-nets, for example, for modelling concurrency\ud
and synchronization properties of systems. This paper claims that techniques that\ud
are adopted within the context of MDA can also be beneficial in modelling systems\ud
by using notations other than the UML. Petri-Nets are widely used for modelling\ud
of business and application logic of information systems with web services. For\ud
certain kinds of applications, therefore, Petri Nets can be more suitable for building\ud
Computation Independent, Platform Independent and Platform Specific Models\ud
(CIM, PIM and PSM). Unfortunately, the well-known problems with separation of\ud
concerns in Petri Nets and keeping track of changes may hinder achieving the aim of\ud
MDA: building reusable, portable and interoperable models. In this paper we define\ud
Aspect Petri Nets as a structure of several Petri Nets and quantification rules for\ud
weaving of those Petri Nets. Aspect Petri Nets are suitable for application of MDA;\ud
they support traceability of changes and reusability, portability and interoperability\ud
of models. We illustrate advantages of modelling in Aspect Petri Nets for MDA\ud
application and describe necessary tool support
Assessment of the effect of the financial crisis on agentsâ expectations through symbolic regression
Agentsâ perceptions on the state of the economy can be affected during economic crises.
Tendency surveys are the main source of agentsâ expectations. The main objective of this study
is to assess the impact of the 2008 financial crisis on agentsâ expectations. With this aim, we
evaluate the capacity of survey-based expectations to anticipate economic growth in the United
States, Japan, Germany and the United Kingdom. We propose a symbolic regression (SR) via
genetic programming approach to derive mathematical functional forms that link survey-based
expectations to GDP growth. By combining the main SR-generated indicators, we generate
estimates of the evolution of GDP. Finally, we analyse the effect of the crisis on the formation
of expectations, and we find an improvement in the capacity of agentsâ expectations to anticipate
economic growth after the crisis in all countries except Germany.Peer ReviewedPostprint (author's final draft
Flow Logic
Flow networks have attracted a lot of research in computer science. Indeed,
many questions in numerous application areas can be reduced to questions about
flow networks. Many of these applications would benefit from a framework in
which one can formally reason about properties of flow networks that go beyond
their maximal flow. We introduce Flow Logics: modal logics that treat flow
functions as explicit first-order objects and enable the specification of rich
properties of flow networks. The syntax of our logic BFL* (Branching Flow
Logic) is similar to the syntax of the temporal logic CTL*, except that atomic
assertions may be flow propositions, like or , for
, which refer to the value of the flow in a vertex, and
that first-order quantification can be applied both to paths and to flow
functions. We present an exhaustive study of the theoretical and practical
aspects of BFL*, as well as extensions and fragments of it. Our extensions
include flow quantifications that range over non-integral flow functions or
over maximal flow functions, path quantification that ranges over paths along
which non-zero flow travels, past operators, and first-order quantification of
flow values. We focus on the model-checking problem and show that it is
PSPACE-complete, as it is for CTL*. Handling of flow quantifiers, however,
increases the complexity in terms of the network to , even
for the LFL and BFL fragments, which are the flow-counterparts of LTL and CTL.
We are still able to point to a useful fragment of BFL* for which the
model-checking problem can be solved in polynomial time. Finally, we introduce
and study the query-checking problem for BFL*, where under-specified BFL*
formulas are used for network exploration
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Quantitative storytelling in the making of a composite indicator
The reasons for and against composite indicators are briefly reviewed, as well as the available theories for their construction. After noting the strong normative dimension of these measuresâwhich ultimately aim to âtell a storyâ, e.g. to promote the social discovery of a particular phenomenon, we inquire whether a less partisan use of a composite indicator can be proposed by allowing more latitude in the framing of its construction. We thus explore whether a composite indicator can be built to tell âmore than one storyâ and test this in practical contexts. These include measures used in convergence analysis in the field of cohesion policies and a recent case involving the World Bankâs Doing Business Index. Our experiments are built to imagine different constituencies and stakeholders who agree on the use of evidence and of statistical information while differing on the interpretation of what is relevant and vital
Quantify resilience enhancement of UTS through exploiting connect community and internet of everything emerging technologies
This work aims at investigating and quantifying the Urban Transport System
(UTS) resilience enhancement enabled by the adoption of emerging technology
such as Internet of Everything (IoE) and the new trend of the Connected
Community (CC). A conceptual extension of Functional Resonance Analysis Method
(FRAM) and its formalization have been proposed and used to model UTS
complexity. The scope is to identify the system functions and their
interdependencies with a particular focus on those that have a relation and
impact on people and communities. Network analysis techniques have been applied
to the FRAM model to identify and estimate the most critical community-related
functions. The notion of Variability Rate (VR) has been defined as the amount
of output variability generated by an upstream function that can be
tolerated/absorbed by a downstream function, without significantly increasing
of its subsequent output variability. A fuzzy based quantification of the VR on
expert judgment has been developed when quantitative data are not available.
Our approach has been applied to a critical scenario (water bomb/flash
flooding) considering two cases: when UTS has CC and IoE implemented or not.
The results show a remarkable VR enhancement if CC and IoE are deploye
Prepare your indicators: Economics imperialism on the shores of law and development
This article explores the influence of economics on the demand for, and deployment of, indicators in the context of the World Bank's investment climate campaign. This campaign is characterised by an emphasis on marketisation, mathematisation and quantification, which are respectively the normative, analytical and empirical approaches of choice in mainstream economics. The article concludes that economics generally, and indicators in particular, have brought a certain discipline and energy to the field of law and development. But this âprogressâ has often been at the expense of non-economic values and interests, and even of our ability to mourn their loss
Survey Expectations
This paper focuses on survey expectations and discusses their uses for testing and modeling of expectations.Alternative models of expectations formation are reviewed and the importance of allowing for heterogeneity of expectations is emphasized. A weak form of the rational expectations hypothesis which focuses on average expectationsrather than individual expectations is advanced. Other models of expectations formation, such as the adaptive expectations hypothesis, are briefly discussed. Testable implications of rational and extrapolative models of expectationsare reviewed and the importance of the loss function for the interpretation of the test results is discussed. The paper thenprovides an account of the various surveys of expectations, reviews alternative methods of quantifying the qualitative surveys, and discusses the use of aggregate and individual survey responses in the analysis of expectations and for forecasting
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