Managing software uninstall with negative trust

A problematic aspect of software management systems in view of integrity preservation is the handling, approval, tracking and eventual execution of change requests. In the context of the relation between clients and repositories, trust can help identifying all packages required by the intended installation. Negative trust, in turn, can be used to approach the complementary problem induced by removing packages. In this paper we offer a logic for negative trust which allows to identify admissible and no-longer admissible software packages in the current installation profile in view of uninstall processes. We provide a simple working example and the system is formally verified using the Coq theorem prover

Small world characteristics of FLOSS distributions

Over the years, Free/Libre Open Source Software (FLOSS) distributions have become more and more complex and recent versions contain tens of thousands of packages. This has made it impossible to do quality control by hand. Instead, distribution editors must look to automated methods to ensure the quality of their distributions. In the present paper, we present some insights into the general structure of FLOSS distributions. We notably show that such distributions have the characteristics of a small world network: there are only a few important packages, and many less important packages. Identifying the important packages can help editors focus their efforts on parts of the distribution where errors will have important consequences

On the correctness of a branch displacement algorithm

The branch displacement problem is a well-known problem in assembler design. It revolves around the feature, present in several processor families, of having different instructions, of different sizes, for jumps of different displacements. The problem, which is provably NP-hard, is then to select the instructions such that one ends up with the smallest possible program. During our research with the CerCo project on formally verifying a C compiler, we have implemented and proven correct an algorithm for this problem. In this paper, we discuss the problem, possible solutions, our specific solutions and the proofs

Using strong conflicts to detect quality issues in component-based complex systems

The mainstream adoption of free and open source software (FOSS) has widely popularised notions like software packages or plugins, maintained in a distributed fashion and evolving at a very quick pace. Each of these components is equipped with metadata, such as dependencies, which define the other components it needs to function properly, and the incompatible components it cannot work with. In this paper, we introduce the notion of strong conflicts, defined from the component dependencies, that can be effectively computed. It gives important insights on the quality issues faced when adding or upgrading components in a given component repository, which is one of the facets of the predictable assembly problem.Our work contains concrete examples drawn from the world of GNU/Linux distributions, that validate the proposed approach. It also shows that the measures defined can be easily applied to the Eclipse world, or to any other coarse-grained software component model

Minimizing transitive trust threats in software management systems

We consider security threats in software installation processes, posed by transitively trusted dependencies between packages from distinct repositories. To analyse them, we present SecureNDC, a Coq implemented calculus using an explicit trust function to bridge repository access and software package installation rights. Thereby, we resolve a version of the minimum install problem under trust conditions on repositorie

Describing and simulating concurrent quantum systems

We present a programming language for describing and analysing concurrent quantum systems. We have an interpreter for programs in the language, using a symbolic rather than a numeric calculator, and we give its performance on examples from quantum communication and cryptography

Teaching functional patterns through robotic applications

We present our approach to teaching functional programming to First Year Computer Science stu- dents at Middlesex University through projects in robotics. A holistic approach is taken to the cur- riculum, emphasising the connections between different subject areas. A key part of the students’ learning is through practical projects that draw upon and integrate the taught material. To support these, we developed the Middlesex Robotic plaTfOrm (MIRTO), an open-source platform built using Raspberry Pi, Arduino, HUB-ee wheels and running Racket (a LISP dialect). In this paper we present the motivations for our choices and explain how a number of concepts of functional programming may be employed when programming robotic applications. We present some students’ work with robotics projects: we consider the use of robotics projects to have been a success, both for their value in reinforcing students’ understanding of programming concepts and for their value in motivating the students

Towards Contagious Animal Disease Detection using Machine Learning

In livestock farms an increasing number of sensors is implemented to monitoring farm production and animal welfare, leading to large amounts of data. We investigated the potential of sensor data for the detection of contagious animal diseases, using machine learning for the interpretation of the data. An ..

Endoscopic biliary sphincterotomy : results, complications and contra-indications

In 1986 the departments of Radiology and Internal Medicine II/Gastroenterology initiated a prospective study of therapeutic endoscopic retrograde cholangiopancreatography (TERCP). The project was designed to obtain information which could be used to evaluate immediate and medium-term results and complications of endoscopic biliary and pancreatic interventions. During a three-year period 1362 consecutive patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) were included, and a large amount of information gathered in a standard, prospective fashion. This information was then used to answer specific questions or solve specific problems, most of which concerned cutting the papilla of Vater during TERCP to improve access to the common bile duct or main pancreatic duct. The main aim of the work reported in this thesis was therefore to evaluate the results of endoscopic biliary sphincterotomy in patients with common bile duct obstruction due to malignancy or stones, with and without cholangitis, and patients suspected of biliary dyskinesia. The studies focussed especially on complications due to the intervention. A general introduction and a review of the literature is given in chapter 2. Chapter 3 describes the patients and the protocol used for the therapeutic ERCP study. In chapter 4 the problems encountered during endoscopic stenting in patients with malignant obstruction of the mid or distal common bile duct and/or the papilla are assessed. Chapter 5 describes the complications observed in patients after endoscopic papillotomy (= endoscopic sphincterotomy) for common bile duct stones and how to prevent them. In chapter 6 the risk factors influencing complications of sphincterotomy in patients with cholangitis due to common bile duct stones are assessed. Follow-up results of endoscopic papillotomy in patients suspected of having a functional disorder of the papilla are described in chapter 7. Patients with a history of Biliroth II gastrectomy present special problem when they have to undergo sphincterotomy. A technique to succesfully perform sphincterotomy in these patients is described in chapter 8. Finally the results and complications of endoscopic papillotomy presented in the previous chapters are discussed and summarized