The 2011 International Planning Competition

After a 3 years gap, the 2011 edition of the IPC involved a total of 55 planners, some of them versions of the same planner, distributed among four tracks: the sequential satisficing track (27 planners submitted out of 38 registered), the sequential multicore track (8 planners submitted out of 12 registered), the sequential optimal track (12 planners submitted out of 24 registered) and the temporal satisficing track (8 planners submitted out of 14 registered). Three more tracks were open to participation: temporal optimal, preferences satisficing and preferences optimal. Unfortunately the number of submitted planners did not allow these tracks to be finally included in the competition. A total of 55 people were participating, grouped in 31 teams. Participants came from Australia, Canada, China, France, Germany, India, Israel, Italy, Spain, UK and USA. For the sequential tracks 14 domains, with 20 problems each, were selected, while the temporal one had 12 domains, also with 20 problems each. Both new and past domains were included. As in previous competitions, domains and problems were unknown for participants and all the experimentation was carried out by the organizers. To run the competition a cluster of eleven 64-bits computers (Intel XEON 2.93 Ghz Quad core processor) using Linux was set up. Up to 1800 seconds, 6 GB of RAM memory and 750 GB of hard disk were available for each planner to solve a problem. This resulted in 7540 computing hours (about 315 days), plus a high number of hours devoted to preliminary experimentation with new domains, reruns and bugs fixing. The detailed results of the competition, the software used for automating most tasks, the source code of all the participating planners and the description of domains and problems can be found at the competition’s web page: http://www.plg.inf.uc3m.es/ipc2011-deterministicThis booklet summarizes the participants on the Deterministic Track of the International Planning Competition (IPC) 2011. Papers describing all the participating planners are included

Métaheuristiques hybrides pour les problèmes de recouvrement et recouvrement partiel d'ensembles appliqués au problème de positionnement des trous de forage dans les mines

RÉSUMÉ La première étape du cycle minier est l’exploration minérale. Dans cette étape, des longs trous de forage sont forés dans les zones de minéralisation pour extraire des échantillons. Les échantillons sont ensuite analysés et un modèle 3D de la distribution des minéraux dans la mine est construit. Puisque le forage coûte très cher, les géologues et ingénieurs miniers tentent de positionner leurs trous d’une façon qui minimise le coût de forage. Par contre, les techniques courantes utilisées pour minimiser le coût de forage sont peu sophistiquées et ne trouvent généralement pas la solution optimale. Dans cette thèse, nous utilisons des techniques de recherche opérationnelle pour résoudre le problème de positionnement des trous de forage dans les mines. Nous modélisons le problème sous forme d’une variante du problème de recouvrement d’ensembles, qui est un problème très populaire en recherche opérationnelle, et résolvons ce problème à l’aide d’algorithmes métaheuristiques, notamment l’algorithme génétique, la recherche locale itérée et la recherche taboue. Pour évaluer l’efficacité de notre approche, nous comparons les solutions trouvées par notre approche aux solutions trouvées par les approches industrielles sur des problèmes réels. Les résultats obtenus montrent que notre approche permet une réduction des coûts de forage allant jusqu’à 35%. Un autre aspect très important de cette thèse est la résolution du problème de recouvrement d’ensembles (SCP) à l’aide de métaheuristiques. Nous proposons une nouvelle formulation du SCP et un nouvel algorithme pour le résoudre. La nouvelle formulation élimine les problèmes de faisabilité et redondances du SCP. Nos expérimentations ont montré que l’algorithme proposé trouve des meilleurs résultats que la majorit (si pas tous) les algorithmes métaheuristiques existants pour le SCP.---------- ABSTRACT The first steps in the mining cycle are exploration and feasibility. In the exploration stage, geologists start by estimating the potential locations of mineral deposits. Then, they drill many long holes inside the mine to extract samples. The samples are then analyzed and a 3D model representing the distribution of mineralization in the mine is constructed. Because drilling is expensive, geologists and mining engineers try to position their drill holes to cover most potential sites with a minimum amount of drilling. However, the current techniques used to position the drill holes are inefficient and do not generally find the optimal solution. In this thesis, we use operations research techniques to solve the drill holes placement problem. We model the drill holes placement problem as a variant of the set covering problem (which is a very popular optimization problem) and solve the modelled problem using the combination of multiple metaheuristic algorithms, namely the genetic algorithm, iterated local search and tabu search. To evaluate the effectiveness of our approach, we compare the solutions found using our approach to the solutions found by industrial approaches on real world problems. The obtained results show that our approach allow saving up to 35% of drilling cost. Another primary aspect of the thesis is the resolution of the set covering problem (SCP) using metaheuristic approaches. We propose a new formulation of the SCP and a new metaheuristic algorithm to solve it. The new formulation is specially designed for metaheuristic approaches and allows solving the SCP without having to deal with feasibility and set redundancy. Computational results show that our metaheuristic approach is more effective than most (if not all) metaheuristic approaches for the SCP

Runtime Quantitative Verification of Self-Adaptive Systems

Software systems used in mission- and business-critical applications in domains including defence, healthcare, and finance must comply with strict dependability, performance, and other Quality-of-Service (QoS) requirements. Self-adaptive systems achieve this compliance under changing environmental conditions, evolving requirements and system failures by using closed-loop control to modify their behaviour and structure in response to these events. Runtime quantitative verification (RQV) is a mathematically-based approach that implements the closed-loop control of self-adaptive systems. Using runtime observations of a system and its environment, RQV updates stochastic models whose formal analysis underpins the adaptation decisions made within the control loop. The approach can identify and, under certain conditions, predict violation of QoS requirements, and can drive self-adaptation in ways guaranteed to restore or maintain compliance with these requirements. Despite its merits, RQV has significant computation and memory overheads, which restrict its applicability to small systems and to adaptations affecting only the configuration parameters of the system. In this thesis, we introduce RQV variants that improve the efficiency and scalability of the approach and extend its applicability to larger and more complex self-adaptive software systems, and to adaptations that modify the structure of a system. First, we integrate RQV with established efficiency improvement techniques from other software engineering areas. We use caching of recent analysis results, limited lookahead to precompute suitable adaptations for potential future changes, and nearly-optimal reconfiguration to eliminate the need for an exhaustive analysis of the entire reconfiguration space. Second, we introduce an RQV variant that incorporates evolutionary algorithms into the RQV process facilitating the efficient search through large reconfiguration spaces and enabling adaptations that include structural changes. Third, we propose an RQV-driven approach that decentralises the control loops in distributed self-adaptive systems. Finally, we devise an RQV-based methodology for the engineering of trustworthy self-adaptive systems. We evaluate the proposed RQV variants using prototype self-adaptive systems from several application domains, including an embedded system for unmanned underwater vehicles and a foreign exchange service-based system. Our results, subject to the adaptation scenarios used in the evaluation, demonstrate the effectiveness and generality of the new RQV variants

The germinal centre artificial immune system

This thesis deals with the development and evaluation of the Germinal centre artificial immune system (GC-AIS) which is a novel artificial immune system based on advancements in the understanding of the germinal centre reaction of the immune system. The key research questions addressed in this thesis are: can an artificial immune system (AIS) be designed by taking inspiration from recent developments in immunology to tackle multi-objective optimisation problems? How can we incorporate desirable features of the immune system like diversity, parallelism and memory into this proposed AIS? How does the proposed AIS compare with other state of the art techniques in the field of multi-objective optimisation problems? How can we incorporate the learning component of the immune system into the algorithm and investigate the usefulness of memory in dynamic scenarios? The main contributions of the thesis are: • Understanding the behaviour and performance of the proposed GC-AIS on multiobjective optimisation problems and explaining its benefits and drawbacks, by comparing it with simple baseline and state of the art algorithms. • Improving the performance of GC-AIS by incorporating a popular technique from multi-objective optimisation. By overcoming its weaknesses the capability of the improved variant to compete with the state of the art algorithms is evaluated. • Answering key questions on the usefulness of incorporating memory in GC-AIS in a dynamic scenario

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks