Generating Complete and Finite Test Suite for ioco: Is It Possible?

Testing from Input/Output Transition Systems has been intensely investigated. The conformance between the implementation and the specification is often determined by the so-called ioco-relation. However, generating tests for ioco is usually hindered by the problem of conflicts between inputs and outputs. Moreover, the generation is mainly based on nondeterministic methods, which may deliver complete test suites but require an unbounded number of executions. In this paper, we investigate whether it is possible to construct a finite test suite which is complete in a predefined fault domain for the classical ioco relation even in the presence of input/output conflicts. We demonstrate that it is possible under certain assumptions about the specification and implementation, by proposing a method for complete test generation, based on a traditional method developed for FSM.Comment: In Proceedings MBT 2014, arXiv:1403.704

Verification of Modular Systems with Unknown Components Combining Testing and Inference

26 pagesVerification of a modular system composed of communicating components is a difficult problem, especially when the formal specifications, i.e., models of the components are not available. Conventional testing techniques are not efficient in detecting erroneous interactions of components because interleavings of internal events are difficult to reproduce in a modular system. The problem of detecting intermittent errors and other compositional problems in the absence of components' models is addressed in this paper. A method to infer a controllable approximation of communicating components through testing is elaborated. The inferred finite state models of components are used to detect compositional problems in the system through reachability analysis. To confirm a flaw in a particular component, a witness trace is used to construct a test applied to the component in isolation. The models are refined at each analysis step thus making the approach iterative

On the accuracy of DFT exchange-correlation functionals for H bonds in small water clusters II: The water hexamer and van der Waals interactions

Second order Moeller-Plesset perturbation theory (MP2) at the complete basis set (CBS) limit and diffusion quantum Monte Carlo (DMC) are used to examine several low energy isomers of the water hexamer. Both approaches predict the so-called "prism" to be the lowest energy isomer, followed by "cage", "book", and "cyclic" isomers. The energies of the four isomers are very similar, all being within 10-15 meV/H2O. This reference data is then used to evaluate the performance of several density-functional theory (DFT) exchange-correlation (xc) functionals. A subset of the xc functionals tested for smaller water clusters [I: Santra et al., J. Chem. Phys. 127, 184104 (2007)] has been considered. Whilst certain functionals do a reasonable job at predicting the absolute dissociation energies of the various isomers (coming within 10-20 meV/H2O), none predict the correct energetic ordering of the four isomers, nor does any predict the correct low total energy isomer. All xc functionals tested either predict the book or cyclic isomers to have the largest dissociation energies. A many-body decomposition of the total interaction energies within the hexamers leads to the conclusion that the failure lies in the poor description of van der Waals (dispersion) forces in the xc functionals considered. It is shown that the addition of an empirical pairwise (attractive) C6/R6 correction to certain functionals allows for an improved energetic ordering of the hexamers. The relevance of these results to density-functional simulations of liquid water is also briefly discussed.Comment: 15 pages including 4 figures; related publications can be found at http://www.fhi-berlin.mpg.de/th/th.htm

Generating minimum height ADSs for partially specified finite state machines

In earlier work, the problem of generating a preset distinguishing sequence from a finite state machine (FSM) was converted into a Boolean formulae to be fed into a SAT solver, with experiments suggesting that such approaches are required as the size of input alphabet grows. In this paper we extend the approach to the minimum height adaptive distinguishing sequence construction problem for partially specified FSMs (PSFMSs), which is known to be an NP- Hard problem. The results of experimentswith randomly generated PSFSMs and case studies from the literature show that SAT solvers can perform better than a previously proposed brute-force algorithm.The Scientific and Technological Research Council of Turkey under the grant reference no B.14.2.TBT.0.06.01-219-115543

Methane Clumped Isotopes: Progress and Potential for a New Isotopic Tracer

The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding petroleum systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. In general, clumped isotope measurements indicate plausible formation temperatures for abiotic, thermogenic, and microbial methane in many geological environments, which is encouraging for the further development of this measurement as a geothermometer, and as a tracer for the source of natural gas reservoirs and emissions. We also highlight, however, instances where clumped isotope derived temperatures are higher than expected, and discuss possible factors that could distort equilibrium formation temperature signals. In microbial methane from freshwater ecosystems, in particular, clumped isotope values appear to be controlled by kinetic effects, and may ultimately be useful to study methanogen metabolism

Refining specifications in adaptive testing of nondeterministic finite state machines

This paper addresses testing of nondeterministic FSMs. An implementation FSM is allowed to be less nondeterministic than its specification, so the reduction relation between machines is the conformance relation. Execution of a given test needs to be adaptive to avoid application of unneeded input sequences, since the test can have different inputs depending on output produced by the implementation under test in response to previous input. To further reduce testing efforts during test execution, the paper suggests performing refinement of the specification FSM by removing traces absent in the implementation, which has already passed some subtest of a given complete (sound and exhaustive) test. The test execution process can be terminated as soon as the executed so far subtest is complete for the current refined version of the specification. The sufficient conditions formulated in the paper can be used for this purpose