Slicing of Concurrent Programs and its Application to Information Flow Control

This thesis presents a practical technique for information flow control for concurrent programs with threads and shared-memory communication. The technique guarantees confidentiality of information with respect to a reasonable attacker model and utilizes program dependence graphs (PDGs), a language-independent representation of information flow in a program

Multi-level Contextual Type Theory

Contextual type theory distinguishes between bound variables and meta-variables to write potentially incomplete terms in the presence of binders. It has found good use as a framework for concise explanations of higher-order unification, characterize holes in proofs, and in developing a foundation for programming with higher-order abstract syntax, as embodied by the programming and reasoning environment Beluga. However, to reason about these applications, we need to introduce meta^2-variables to characterize the dependency on meta-variables and bound variables. In other words, we must go beyond a two-level system granting only bound variables and meta-variables. In this paper we generalize contextual type theory to n levels for arbitrary n, so as to obtain a formal system offering bound variables, meta-variables and so on all the way to meta^n-variables. We obtain a uniform account by collapsing all these different kinds of variables into a single notion of variabe indexed by some level k. We give a decidable bi-directional type system which characterizes beta-eta-normal forms together with a generalized substitution operation.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

KONZO : the IBRO Africa Regional Committee (ARC) organizes its first Global Advocacy Workshop for Neuroscience in Kinshasa

Neurological diseases such as epilepsy, konzo, or neurolathyrism are not well understood or even accepted as major causes of disability. It is important that the public – from parents and children to politicians and policymakers – be informed about the importance of brain research and how it can help understand the causes and develop cures or, at least, alleviate the symptoms of neurological diseases

Many-Task Computing and Blue Waters

This report discusses many-task computing (MTC) generically and in the context of the proposed Blue Waters systems, which is planned to be the largest NSF-funded supercomputer when it begins production use in 2012. The aim of this report is to inform the BW project about MTC, including understanding aspects of MTC applications that can be used to characterize the domain and understanding the implications of these aspects to middleware and policies. Many MTC applications do not neatly fit the stereotypes of high-performance computing (HPC) or high-throughput computing (HTC) applications. Like HTC applications, by definition MTC applications are structured as graphs of discrete tasks, with explicit input and output dependencies forming the graph edges. However, MTC applications have significant features that distinguish them from typical HTC applications. In particular, different engineering constraints for hardware and software must be met in order to support these applications. HTC applications have traditionally run on platforms such as grids and clusters, through either workflow systems or parallel programming systems. MTC applications, in contrast, will often demand a short time to solution, may be communication intensive or data intensive, and may comprise very short tasks. Therefore, hardware and software for MTC must be engineered to support the additional communication and I/O and must minimize task dispatch overheads. The hardware of large-scale HPC systems, with its high degree of parallelism and support for intensive communication, is well suited for MTC applications. However, HPC systems often lack a dynamic resource-provisioning feature, are not ideal for task communication via the file system, and have an I/O system that is not optimized for MTC-style applications. Hence, additional software support is likely to be required to gain full benefit from the HPC hardware

An Analysis of the Current Program Slicing and Algorithmic Debugging Based Techniques

This thesis presents a classification of program slicing based techniques. The classification allows us to identify the differences between existing techniques, but it also allows us to predict new slicing techniques. The study identifies and compares the dimensions that influence current techniques.Silva Galiana, JF. (2008). An Analysis of the Current Program Slicing and Algorithmic Debugging Based Techniques. http://hdl.handle.net/10251/14300Archivo delegad

Validity and usability of a virtual reality intraocular surgical simulator

Cataract surgery is one of the most common surgical procedures in Sweden and around 90 000 operations are made each year. An aging population with increased demands on quality of life and good visual acuity, has led to an increased rate of surgery and more surgeons needs to be trained. Training of new cataract surgeons is done on scarce wet-lab training but mainly on patients. Training is costly and complications are higher for new surgeons compared to experienced ones. In the airline industry simulators are used for training. Pilots have to prove competent before flying a new airplane. No such standards exist for new cataract surgeons. Surgical simulators have been used in other surgical fields for training and reports have shown that training has improved performance on real operations. The purpose of this work was to validate Eyesi, a surgical simulator for cataract surgery training, and analyze learning curves. Furthermore we set out to investigate whether factors like stereoacuity and sex would be important for performance in the simulator. Evidence for construct validity was found for cataract specific modules capsulorhexis, hydromaneuvers and phaco divide and conquer and for manipulating modules cataract navigation training, cataract forceps training and cataract cracking and chopping training. Analysis of learning curves showed significant improvement throughout training. Evidence for concurrent validity was established for the capsulorhexis module. For the hydromaneuvers and phaco modules, the innate simulator scoring could not distinguish surgical skill but discrimination was dependent on video based human scoring. Stereoacuity was found to correlate with performance on the simulator but there were large individual variations. An individual’s sex had no influence on performance. We have shown that Eyesi can differentiate cataract surgical skill and that naïve can train in the simulator and improve. Stereoacuity has an effect on performance but there were large individual variations. Simulation-based training has the potential to move the early learning curve out of the operating room

Model Checking with Program Slicing Based on Variable Dependence Graphs

In embedded control systems, the potential risks of software defects have been increasing because of software complexity which leads to, for example, timing related problems. These defects are rarely found by tests or simulations. To detect such defects, we propose a modeling method which can generate software models for model checking with a program slicing technique based on a variable dependence graph. We have applied the proposed method to one case in automotive control software and demonstrated the effectiveness of the method. Furthermore, we developed a software tool to automate model generation and achieved a 35% decrease in total verification time on model checking.Comment: In Proceedings FTSCS 2012, arXiv:1212.657