Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing

Recent years have seen the utilisation of Semantic Web Service descriptions for automating a wide range of service-related activities, with a primary focus on service discovery, composition, execution and mediation. An important area which so far has received less attention is service validation, whereby advertised services are proven to conform to required behavioural specifications. This paper proposes a method for validation of service-oriented systems through automated functional testing. The method leverages ontology-based and rule-based descriptions of service inputs, outputs, preconditions and effects (IOPE) for constructing a stateful EFSM specification. The specification is subsequently utilised for functional testing and validation using the proven Stream X-machine (SXM) testing methodology. Complete functional test sets are generated automatically at an abstract level and are then applied to concrete Web services, using test drivers created from the Web service descriptions. The testing method comes with completeness guarantees and provides a strong method for validating the behaviour of Web services

A functional specification of effects

This dissertation is about effects and type theory. Functional programming languages such as Haskell illustrate how to encapsulate side effects using monads. Haskell compilers provide a handful of primitive effectful functions. Programmers can construct larger computations using the monadic return and bind operations. These primitive effectful functions, however, have no associated definition. At best, their semantics are specified separately on paper. This can make it difficult to test, debug, verify, or even predict the behaviour of effectful computations. This dissertation provides pure, functional specifications in Haskell of several different effects. Using these specifications, programmers can test and debug effectful programs. This is particularly useful in tandem with automatic testing tools such as QuickCheck. The specifications in Haskell are not total. This makes them unsuitable for the formal verification of effectful functions. This dissertation overcomes this limitation, by presenting total functional specifications in Agda, a programming language with dependent types. There have been alternative approaches to incorporating effects in a dependently typed programming language. Most notably, recent work on Hoare Type Theory proposes to extend type theory with axioms that postulate the existence of primitive effectful functions. This dissertation shows how the functional specifications implement these axioms, unifying the two approaches. The results presented in this dissertation may be used to write and verify effectful programs in the framework of type theory

Economic Development and CO2 Emissions: A Nonparametric Panel Approach

We examine the empirical relation between CO2 emissions per capita and GDP per capita during the period 1960-1996, using a panel of 100 countries. Relying on the nonparametric poolability test of Baltagi et al. (1996), we find evidence of structural stability of the relationship. We then specify a nonparametric panel data model with country-specific effects. Estimation results show that this relationship is upward sloping. Nonparametric specification tests do not reject monotonicity but do reject the polynomial functional form which leads to the environmental Kuznets curve in several studies. --Environmental Kuznets curve,panel data,poolability test,mono- tonicity test,specification test

A functional specification of effects

This dissertation is about effects and type theory. Functional programming languages such as Haskell illustrate how to encapsulate side effects using monads. Haskell compilers provide a handful of primitive effectful functions. Programmers can construct larger computations using the monadic return and bind operations. These primitive effectful functions, however, have no associated definition. At best, their semantics are specified separately on paper. This can make it difficult to test, debug, verify, or even predict the behaviour of effectful computations. This dissertation provides pure, functional specifications in Haskell of several different effects. Using these specifications, programmers can test and debug effectful programs. This is particularly useful in tandem with automatic testing tools such as QuickCheck. The specifications in Haskell are not total. This makes them unsuitable for the formal verification of effectful functions. This dissertation overcomes this limitation, by presenting total functional specifications in Agda, a programming language with dependent types. There have been alternative approaches to incorporating effects in a dependently typed programming language. Most notably, recent work on Hoare Type Theory proposes to extend type theory with axioms that postulate the existence of primitive effectful functions. This dissertation shows how the functional specifications implement these axioms, unifying the two approaches. The results presented in this dissertation may be used to write and verify effectful programs in the framework of type theory

Another look at the inflation-productivity trade-off

Our aim in this paper is to test the robustness of the relation between total factor productivity growth and inflation to the specification of the model adopted for its identification. In doing so we estimate a generalized Box-Box cost function using data from the two-digit Standard Industrial Classification of manufacturing industries in Greece during the period 1964-1980. The results confirm that the acceleration of inflation from 1964-1972 to 1973-1980 reduced total factor productivity growth in a way that was both statistically significant and sizeable. In addition, they reveal that, even when the effect of inflation is separated from the effects of technical change and economies of scale, the choice of functional form is most crucial. The reason being that cost functions such as the translog, the generalized Leontief, and the generalized square root quadratic are not general enough to account for the sensitivity of estimates to model specification. On these grounds then we conclude that, for a precise estimation of the adverse impact of inflation on total factor productivity growth, it is imperative both to sort out the three effects involved and do so by adopting the most general flexible functional form available for the cost function.inflation, total factor productivity, generalized Box-Cox cost function, economic growth

Nonparametric Stochastic Volatility

Using recent advances in the nonparametric estimation of continuous-time processes under mild statistical assumptions as well as recent developments on nonparametric volatility estimation by virtue of market microstructure noise-contaminated high-frequency asset price data, we provide (i) a theory of spot variance estimation and (ii) functional methods for stochastic volatility modelling. Our methods allow for the joint evaluation of return and volatility dynamics with nonlinear drift and diffusion functions, nonlinear leverage effects, jumps in returns and volatility with possibly state-dependent jump intensities, as well as nonlinear risk-return trade-offs. Our identification approach and asymptotic results apply under weak recurrence assumptions and, hence, accommodate the persistence properties of variance in finite samples. Functional estimation of a generalized (i.e., nonlinear) version of the square-root stochastic variance model with jumps in both volatility and returns for the S&P500 index suggests the need for richer variance dynamics than in existing work. We find a linear specification for the variance's diffusive variance to be misspecified (and inferior to a more flexible CEV specification) even when allowing for jumps in the variance dynamics.Spot variance, stochastic volatility, jumps in returns, jumps in volatility, leverage effects, risk-return trade-offs, kernel methods, recurrence, market microstructure noise.

How wrong can you be? Implications of incorrect utility function specification for welfare measurement in choice experiments

Despite the vital role of the utility function in welfare measurement, the implications of working with incorrect utility specifications have been largely neglected in the choice experiments literature. This paper addresses the importance of specification with a special emphasis on the effects of mistaken assumptions about the marginal utility of income. Monte Carlo experiments were conducted using different functional forms of utility to generate simulated choices. Multi-Nomial Logit and Mixed Logit models were then estimated on these choices under correct and incorrect assumptions about the true, underlying utility function. Estimated willingness to pay measures from these choice modelling results are then compared with the equivalent measures directly calculated from the true utility specifications. Results show that for the parameter values and functional forms considered, a continuous-quadratic or a discrete-linear attribute specification is a good option regardless of the true effects the attribute has on utility. We also find that mistaken assumptions about preferences over costs magnify attribute mis-specification effects

The probabilistic reduction approach to specifying multinomial logistic regression models in health outcomes research

The paper provides a novel application of the probabilistic reduction (PR) approach to the analysis of multi-categorical outcomes. The PR approach, which systematically takes account of heterogeneity and functional form concerns, can improve the specification of binary regression models. However, its utility for systematically enriching the specification of and inference from models of multi-categorical outcomes has not been examined, while multinomial logistic regression models are commonly used for inference and, increasingly, prediction. Following a theoretical derivation of the PR-based multinomial logistic model (MLM), we compare functional specification and marginal effects from a traditional specification and a PR-based specification in a model of post-stroke hospital discharge disposition and find that the traditional MLM is misspecified. Results suggest that the impact on the reliability of substantive inferences from a misspecified model may be significant, even when model fit statistics do not suggest a strong lack of fit compared with a properly specified model using the PR approach. We identify situations under which a PR-based MLM specification can be advantageous to the applied researcher

Nonstationarity in the Specification of the Environmental Kuznets Curve

Numerous studies have addressed the question of the econometric specification of the Environmental Kuznets Curve (EKC). This paper adds preliminary results on nonstationarity and its effect on functional form using a panel data set for the U.S. by state from 1929 to 1994. It is found that unit-root tests strongly support a unit root in pollutants (sulfur dioxide and nitrogen oxide) and income when testing individual states. The results from panel data unit root tests provide mixed evidence about nonstationarity in EKC data.Environmental Kuznets curve, fixed and random effects, parametric models, water pollution, watershed, nonstationarity, unit-roots, Environmental Economics and Policy,