Model checking learning agent systems using Promela with embedded C code and abstraction

As autonomous systems become more prevalent, methods for their verification will become more widely used. Model checking is a formal verification technique that can help ensure the safety of autonomous systems, but in most cases it cannot be applied by novices, or in its straight \off-the-shelf" form. In order to be more widely applicable it is crucial that more sophisticated techniques are used, and are presented in a way that is reproducible by engineers and verifiers alike. In this paper we demonstrate in detail two techniques that are used to increase the power of model checking using the model checker SPIN. The first of these is the use of embedded C code within Promela specifications, in order to accurately re ect robot movement. The second is to use abstraction together with a simulation relation to allow us to verify multiple environments simultaneously. We apply these techniques to a fairly simple system in which a robot moves about a fixed circular environment and learns to avoid obstacles. The learning algorithm is inspired by the way that insects learn to avoid obstacles in response to pain signals received from their antennae. Crucially, we prove that our abstraction is sound for our example system { a step that is often omitted but is vital if formal verification is to be widely accepted as a useful and meaningful approach

Comparing Defeasible Argumentation and Non-Monotonic Fuzzy Reasoning Methods for a Computational Trust Problem with Wikipedia

Computational trust is an ever-more present issue with the surge in autonomous agent development. Represented as a defeasible phenomenon, problems associated with computational trust may be solved by the appropriate reasoning methods. This paper compares two types of such methods, Defeasible Argumentation and Non-Monotonic Fuzzy Logic to assess which is more effective at solving a computational trust problem centred around Wikipedia editors. Through the application of these methods with real-data and a set of knowledge-bases, it was found that the Fuzzy Logic approach was statistically significantly better than the Argumentation approach in its inferential capacity

Applying model checking to agent-based learning systems

In this thesis we present a comprehensive approach for applying model checking to Agent-Based Learning (ABL) systems. Model checking faces a unique challenge with ABL systems, as the modelling of learning is thought to be outwith its scope. The practical work performed to model these systems is presented in the incremental stages by which it was carried out. This allows for a clearer understanding of the problems faced and of the progress made on traditional ABL system analysis. Our focus is on applying model checking to a specific type of system. It involves a biologically-inspired robot that uses Input Correlation learning to help it navigate environments. We present a highly detailed PROMELA model of this system, using embedded C code to avoid losing accuracy when modelling it. We also propose an abstraction method for this type of system: Agent-centric abstraction. Our abstraction is the main contribution of this thesis. It is defined in detail, and we provide a proof of its soundness in the form of a simulation relation. In addition to this, we use it to generate an abstract model of the system. We give a comparison between our models and traditional system analysis, specifically simulation. A strong case for using model checking to aid ABL system analysis is made by our comparison and the verification results we obtain from our models. Overall, we present a framework for analysing ABL systems that differs from the more common approach of simulation. We define this framework in detail, and provide results from practical work coupled with a discussion about drawbacks and future enhancements

Second trimester hepatic rupture in a 35 year old nulliparous woman with HELLP syndrome: a case report

The HELLP syndrome (haemolysis, elevated liver blood tests and low platelets) is a serious complication in pregnancy characterized by haemolysis, elevated liver enzymes and low platelet count occurring in 0.5 to 0.9% of all pregnancies and in 10–20% of cases with severe preeclampsia. Hepatic capsular rupture is a rare yet dramatic complication of HELLP syndrome. The majority of cases occur in multiparous women over the age of 30. Classically it presents with acute onset right upper quadrant pain in the presence of constitutional symptoms such as vomiting and pyrexia. However, symptoms and signs are usually non specific. Spontaneous hepatic rupture can be preceded by signs of hypovolaemic shock; yet the diagnosis is infrequently made prior to emergent laparotomy. We present the case of a 35 year old nulliparous woman with a second trimester gestational hepatic rupture associated with HELLP syndrome. We briefly discuss the aetiology, diagnostic difficulties and treatment options associated with this rare presentation

Progress on Model Checking Robot Behaviour

Abstract: We model systems that involve a learning robot which interacts with obstacles in a static environment. Our models are specified in Promela with a view to verifying them using SPI

Stimulate the Adoption of Solar PV on Nantucket

Two undersea cables provide Nantucket with electricity, but a third cable may be needed in the future to accommodate peak summer demands. To avoid this eventuality Nantucket is exploring a variety of options, including the adoption of renewable energies in conjunction with energy storage systems to enhance energy independence. The goal of our project was to assist the Nantucket Energy Office in promoting the adoption of photovoltaics on Nantucket. We conducted research, interviewed stakeholders, and distributed a survey to local residents to identify the current barriers to solar PV on Nantucket. We developed web-based promotional materials, including an interactive map, solar PV owner profiles, and a comprehensive list of FAQs, and recommended improvements to the permitting process

Frequent Storm Surges Affect the Groundwater of Coastal Ecosystems

Recent studies have focused on the effect of large tropical cyclones (hurricanes) on the shore, neglecting the role of less intense but more frequent events. Here we analyze the effect of the offshore tropical storm Melissa on groundwater data collected along the North America Atlantic coast. Our meta-analysis indicates that both groundwater level and specific conductivity significantly increased during Melissa, respectively reaching maximum values of 1.09 m and 25.2 mS/cm above pre-storm levels. Time to recover to pre-storm levels was 10 times greater for groundwater specific conductivity, with a median value of 20 days, while groundwater level had a median recovery time of 2 days. A frequency-magnitude analysis indicates that the percent of time with salinization is higher for Melissa than for energetic hurricanes. Given the high frequency of these events (return period of 1–2 years), and the long time needed for groundwater conditions to return to normal levels, we conclude that increasingly frequent moderate storms will have a significant impact on the ecology of vegetated shorelines

Physiological and metabolic characteristics of elite tug of war athletes

Objective—To determine the aerobic power ([Image: see text] O(2)MAX), body composition, strength, muscular power, flexibility, and biochemical profile of an elite international squad of tug of war athletes. Methods—Sixteen male competitors (mean (SEM) age 34 (2) years) were evaluated in a laboratory. For comparative purposes, data were analysed relative to normative data for our centre and to a group of 20 rugby forwards from the Irish international squad. Results—The tug of war participants were lighter (83.6 (3.0) v 104.4 (1.8) kg, p<0.0001) and had less lean body mass (69.4 (2.1) v 86.2 (1.2) kg) than the rugby players and had lower than normal body fat (16.7 (0.9)%); all values are mean (SEM). Aerobic power measured during a treadmill test was 55.8 (1.6) ml/kg/min for the tug of war participants compared with 51.1 (1.4) ml/kg/min for the rugby forwards (p<0.03). A composite measure of strength derived from (sum of dominant and non-dominant grip strength and back strength)/lean body mass yielded a strength/mass ratio that was 32% greater (p<0.0001) for the tug of war group than the rugby group. Dynamic leg power was lower for the tug of war group than the rugby forwards (4659.8 (151.6) v 6198.2 (105) W respectively; p<0.0001). Leg flexibility was 25.4 (2.0) cm for the tug of war group. Back flexibility was 28.6 (1.4) cm which was lower (p<0.02) than the rugby forwards 34.2 (1.5) cm. Whereas blood chemistry and haematology were normal, packed cell volume, haemoglobin concentration, and erythrocyte volume were lower in the tug of war group than in the rugby players (p<0.05). All three haematological measures correlated with muscle mass (packed cell volume, r(2) = 0.37, p<0.0001; haemoglobin concentration, r(2) = 0.13, p<0.05; erythrocyte volume, r(2) = 0.21, p<0.01). Conclusions—The data indicate that international level tug of war participants have excellent strength and above average endurance relative to body size, but have relatively low explosive leg power and back flexibility. The data provide reference standards for the sport and may be useful for monitoring and evaluating current and future participants. Key Words: tug of war; body composition; [Image: see text] O(2)MAX; strength; power; flexibilit