Exploration of the scalability of LocFaults approach for error localization with While-loops programs

A model checker can produce a trace of counterexample, for an erroneous program, which is often long and difficult to understand. In general, the part about the loops is the largest among the instructions in this trace. This makes the location of errors in loops critical, to analyze errors in the overall program. In this paper, we explore the scala-bility capabilities of LocFaults, our error localization approach exploiting paths of CFG(Control Flow Graph) from a counterexample to calculate the MCDs (Minimal Correction Deviations), and MCSs (Minimal Correction Subsets) from each found MCD. We present the times of our approach on programs with While-loops unfolded b times, and a number of deviated conditions ranging from 0 to n. Our preliminary results show that the times of our approach, constraint-based and flow-driven, are better compared to BugAssist which is based on SAT and transforms the entire program to a Boolean formula, and further the information provided by LocFaults is more expressive for the user

Neuromuscular study of early branching <i>Diuronotus aspetos</i> (Paucitubulatina) yields insights into the evolution of organs systems in Gastrotricha

BACKGROUND: Diuronotus is one of the most recently described genera of Paucitubulatina, one of the three major clades in Gastrotricha. Its morphology suggests that Diuronotus is an early branch of Paucitubulatina, making it a key taxon for understanding the evolution of this morphologically understudied group. Here we test its phylogenetic position employing molecular data, and provide detailed descriptions of the muscular, nervous, and ciliary systems of Diuronotus aspetos, using immunohistochemistry and confocal laser scanning microscopy. RESULTS: We confirm the proposed position of D. aspetos within Muselliferidae, and find this family to be the sister group to Xenotrichulidae. The muscular system, revealed by F-actin staining, shows a simple, but unique organization of the trunk musculature with a reduction to three pairs of longitudinal muscles and addition of up to five pairs of dorso-ventral muscles, versus the six longitudinal and two dorso-ventral pairs found in most Paucitubulatina. Using acetylated α-tubulin immunoreactivity, we describe the pharynx in detail, including new nervous structures, two pairs of sensory cilia, and a unique canal system. The central nervous system, as revealed by immunohistochemistry, shows the general pattern of Gastrotricha having a bilobed brain and a pair of ventro-longitudinal nerve cords. However, in addition are found an anterior nerve ring, several anterior longitudinal nerves, and four ventral commissures (pharyngeal, trunk, pre-anal, and terminal). Two pairs of protonephridia are documented, while other Paucitubulatina have one. Moreover, the precise arrangement of multiciliated cells is unraveled, yielding a pattern of possibly systematic importance. CONCLUSION: Several neural structures of Diuronotus resemble those found in Xenotrichula (Xenotrichulidae) and may constitute new apomorphies of Paucitubulatina, or even Gastrotricha. In order to test these new evolutionary hypotheses, comparable morphological data from other understudied gastrotrich branches and a better resolution of the basal nodes of the gastrotrich phylogeny are warranted. Nonetheless, the present study offers new insights into the evolution of organ systems and systematic importance of so-far neglected characters in Gastrotricha

Negotiating differences in academic preparedness among transnational students in higher education

“Students these days don’t know anything,” commented a faculty member in a focus group. But is it that students don’t know anything, or that faculty members are unfamiliar with what students do know? This is no small issue, as the acceleration of internationalization in higher education and the broader processes of globalization have led to increased numbers of students with general education profiles that differ from those of the instructors and their domestic students. These transnational students—not only international students (paying international tuition), but also permanent residents and citizens —received their primary and secondary (and, possibly, undergraduate) educations outside of Canada, and instructors often lack an awareness of their educational backgrounds and experiences. Emerging from a study of the everyday instructional needs of full-time college and university faculty, this paper presents the results of a systematic review of the literature on the general education of students from four regions that are sources of international students and immigrants, and, therefore, prepared students on campus: China, India, the Middle East, and Latin America. The research not only identifies the curriculum that these students followed, but also the impact of educational reforms on the teaching styles and learning skills emphasized in these systems, and describes the implications for Canadian instructors

Modeling of the Behavior of Expansive Soils

In the preliminary reconnaissance phase and once the swelling of soil is suspected, it is possible to obtain an estimation of swelling parameters (amplitude and pressure) using numerous rheological models proposed in the literature. These models relate the parameters of swelling to the geotechnical parameters determined from mechanical tests. The analysis of the behavior of clays is conducted by numerical simulation tests of compression and swelling by using the oedometer. This analysis is conducted using the software CASTEM2000 team from CEA-France. This simulation allows-among others-to develop a predictive procedure for estimating the parameters of swelling by the use of constitutive equations of Cam-Clay and Alonso. It should be noted that different simulations are performed; those using oedometer tests by the Cam- Clay model, and Alonso and free swell tests by the Alonso model. The results of this work show that the compressibility has been correctly simulated by both models. The phase of swelling has been simulated by the model of Alonso as the Cam-Clay model can simulate it. It should be noted that the Alonso model underestimates very fluffy swelling soils

Experimental characterization of clay soils behavior stabilized by polymers

In this work, we propose to use both PVC and HDPE polymers such additions in cohesive soils to determine their influence on the physical and mechanical properties of soil-polymer material in function of time, which should insure some optimal period of life. For this purpose, different tests including Atterberg Limits, standard compaction, swelling potential, and swelling pressure, were conducted on control and treated soil samples using different Percentage of Polymer (PVC and HDPE) (0, 3 and 6%). Also California Bearing Ratio (CBR) tests were conducted on control and treated samples. The results showed that soil treatment with PVC and HDPE, resulted in improvement of CBR and maximum dry density and reduction in Atterberg Limits, swelling potential and swelling pressure. The addition of a small percentage of polymer causes initially at (t =0 sec) an instantaneous of deformation (elastic response), followed by a time-dependent deformation with the speed of the increasing deformation.Keywords: Mechanic; Polymer; Expansive clay; Optimum; Compressibilit

LocFaults: A new flow-driven and constraint-based error localization approach

International audienceWe introduce in this paper LocFaults, a new flow-driven and constraint-based approach for error localization. The input is a faulty program for which a counter-example and a postcondition are provided. To identify helpful informa-tion for error location, we generate a constraint system for the paths of the control flow graph for which at most k con-ditional statements may be erroneous. Then, we calculate Minimal Correction Sets (MCS) of bounded size for each of these paths. The removal of one of these sets of constraints yields a maximal satisfiable subset, in other words, a max-imal subset of constraints satisfying the post condition. To compute the MCS, we extend the algorithm proposed by Liffiton and Sakallah [21] in order to handle programs with numerical statements more efficiently. The main advantage of this flow-driven approach is that the computed sets of suspicious instructions are small, each of them being asso-ciated with an identified path. Moreover, the constraint-programming based framework of LocFaults allows mix-ing Boolean and numerical constraints in an efficient and straightforward way. Preliminary experiments are quite en-couraging. * This work was partially supported by ANR VAC-SIM (ANR-11-INSE-0004), ANR AEOLUS (ANR-10-SEGI-0013), and OSEO ISI PAJERO projects