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Intelligent Multiobjective Optimization of Distribution System Operations

AI Magazine

Also, it provides a means for conflict resolution of multiple criteria and better assessment of options. This system provides identification, recognition, optimization, a very powerful solution methodology by permitting and control. The algorithmic methods optimization of power distribution system provide updates to the system status operation (Sarfi and Solo 2005a). Sarfi, Salama, and Chikhani (1994a) as well as system with a coupling between knowledgebased Sarfi and Solo (2002c) demonstrate that fuzzy and numerical methods combines the logic is not an asset in all power systems planning advantages of both methods for multiobjective and operation scenarios. Some rules do optimization of power distribution system not involve any uncertainty or can be represented operation. One must to ensure that the best methods are employed. An extensive study of software effectively optimizes a power distribution network tools used in real-time power system for multiple system-performance objectives, applications concluded that electric utility including system loss reduction, transformer companies were not satisfied with conventional load balancing, reduction of transformer approaches based on numerical methods in aging to decrease the failure rate and 50 percent of the cases examined (Sarfi, Salama, increase continuity of service, maintenance of and Chikhani 1994a). Dissatisfied parties a satisfactory voltage profile throughout the cited two major shortcomings in techniques network, reactive power compensation, and based on numerical methods: (1) lack of flexibility conservative voltage reduction (CVR) practice in system modeling, and (2) exclusion of to achieve peak shaving.


The AAAI 2005 Mobile Robot Competition and Exhibition

AI Magazine

Two overarching goals were promoted for the 2005 Mobile Robot Competition. The first was to give the competitions an exhibitionstyle format to make them as accessible to different areas of research as possible. This was change would place the competitions and exhibitions demonstrated at the Fourteenth Annual AAAI directly in line with the conference, Mobile Robot Competition and Exhibition, an teams would need to handle the challenges involved event hosted at the Twentieth National Conference with noisy, cluttered, and unstructured on Artificial Intelligence (AAAI 2005). The robot event had a particularly strong human environments. Scavenger Hunt: Autonomous robots were required to search a cluttered and crowded environment This year, AAAI changed the venue format for a defined list of objects and were from a convention center to a hotel setting. The Scavenger as defined by the team, and feedback Hunt event was organized by Douglas from the participants. Blank from Bryn Mawr College, the Robot Robot Challenge: Robots were required to attend Challenge and the Open Interaction Task were the conference autonomously, including organized by Ashley Stroupe from the Jet registering for the conference, navigating the Propulsion Laboratory, the research component conference hall, talking with attendees, and of the exhibition was organized by Magdalena answering questions.


AI and the News

AI Magazine

Capek's seminal play can be used to explore with links to the item's source and Boryana Rossa and her colleagues sent And the staff Please note that: (1) an excerpt may not 50 Years. It reflect the overall tenor of the item, nor 18, 2006 (thedartmouth.com). "Fifty years should be considered a sin, the decree said, contain all of the relevant information; after a group of about 10 young scientists to kill an artificially created, sentient being and, (2) all items are offered "as is" and first met to start the nascent field of artificial (that is, a robot). Robots have the right to the fact that an item has been selected does intelligence, some of them returned chose their own religion, it continued. An not imply any endorsement whatsoever. 'In terms of artificial Italy, and announced their initial findings said. 'The idea that a machine could intelligence, you can't have an intelligent in March at the European Robotics Symposium do things that before we thought only humans entity without the possibility of free will,' in Palermo, Sicily. 'It has to have choices and intentions, is being done to protect us from Since then, computers have otherwise it is like a toaster.' … Ultrafuturo these mechanical menaces? 'Not enough,' tackled calculus, chess and even had some critiques science, specifically the says Blay Whitby, an artificial-intelligence success at translating languages. There are uses of artificial intelligence and the responsibilities expert at the University of Sussex in England. But … Robot safety is likely to surface in assistance."


Report on the First International Conference on Human-Robot Interaction (HRI)

AI Magazine

(see figure 1). Woods delivered a talk titled "The Law of Stretched Systems Nass delivered a talk titled "Every Body Is Somebody: The Psychology and Design of Embodiment" The best poster award to solve critical challenges in went to "Challenges to Grounding in socially relevant problems. These efforts Human-Robot Interaction" by K. are inherently interdisciplinary, Stubbs, P. Hinds, and D. Wettergreen. How Humans Teach" by A. on human-robot interaction HRI2006 was the first step toward Thomaz, G. Hoffman, and C. Breazeal. The conference forum for the presentation of research about 150 representatives from was sponsored by the Associaman-robot results on leading-edge issues of hu-academe, government, and industry.


Engineering Benchmarks for Planning: the Domains Used in the Deterministic Part of IPC-4

Journal of Artificial Intelligence Research

In a field of research about general reasoning mechanisms, it is essential to have appropriate benchmarks. Ideally, the benchmarks should reflect possible applications of the developed technology. In AI Planning, researchers more and more tend to draw their testing examples from the benchmark collections used in the International Planning Competition (IPC). In the organization of (the deterministic part of) the fourth IPC, IPC-4, the authors therefore invested significant effort to create a useful set of benchmarks. They come from five different (potential) real-world applications of planning: airport ground traffic control, oil derivative transportation in pipeline networks, model-checking safety properties, power supply restoration, and UMTS call setup. Adapting and preparing such an application for use as a benchmark in the IPC involves, at the time, inevitable (often drastic) simplifications, as well as careful choice between, and engineering of, domain encodings. For the first time in the IPC, we used compilations to formulate complex domain features in simple languages such as STRIPS, rather than just dropping the more interesting problem constraints in the simpler language subsets. The article explains and discusses the five application domains and their adaptation to form the PDDL test suites used in IPC-4. We summarize known theoretical results on structural properties of the domains, regarding their computational complexity and provable properties of their topology under the h+ function (an idealized version of the relaxed plan heuristic). We present new (empirical) results illuminating properties such as the quality of the most wide-spread heuristic functions (planning graph, serial planning graph, and relaxed plan), the growth of propositional representations over instance size, and the number of actions available to achieve each fact; we discuss these data in conjunction with the best results achieved by the different kinds of planners participating in IPC-4.


Multiple-Goal Heuristic Search

Journal of Artificial Intelligence Research

This paper presents a new framework for anytime heuristic search where the task is to achieve as many goals as possible within the allocated resources. We show the inadequacy of traditional distance-estimation heuristics for tasks of this type and present alternative heuristics that are more appropriate for multiple-goal search. In particular, we introduce the marginal-utility heuristic, which estimates the cost and the benefit of exploring a subtree below a search node. We developed two methods for online learning of the marginal-utility heuristic. One is based on local similarity of the partial marginal utility of sibling nodes, and the other generalizes marginal-utility over the state feature space. We apply our adaptive and non-adaptive multiple-goal search algorithms to several problems, including focused crawling, and show their superiority over existing methods.


Clause/Term Resolution and Learning in the Evaluation of Quantified Boolean Formulas

Journal of Artificial Intelligence Research

Resolution is the rule of inference at the basis of most procedures for automated reasoning. In these procedures, the input formula is first translated into an equisatisfiable formula in conjunctive normal form (CNF) and then represented as a set of clauses. Deduction starts by inferring new clauses by resolution, and goes on until the empty clause is generated or satisfiability of the set of clauses is proven, e.g., because no new clauses can be generated. In this paper, we restrict our attention to the problem of evaluating Quantified Boolean Formulas (QBFs). In this setting, the above outlined deduction process is known to be sound and complete if given a formula in CNF and if a form of resolution, called ``Q-resolution'', is used. We introduce Q-resolution on terms, to be used for formulas in disjunctive normal form. We show that the computation performed by most of the available procedures for QBFs --based on the Davis-Logemann-Loveland procedure (DLL) for propositional satisfiability-- corresponds to a tree in which Q-resolution on terms and clauses alternate. This poses the theoretical bases for the introduction of learning, corresponding to recording Q-resolution formulas associated with the nodes of the tree. We discuss the problems related to the introduction of learning in DLL based procedures, and present solutions extending state-of-the-art proposals coming from the literature on propositional satisfiability. Finally, we show that our DLL based solver extended with learning, performs significantly better on benchmarks used in the 2003 QBF solvers comparative evaluation.


Temporal Planning using Subgoal Partitioning and Resolution in SGPlan

Journal of Artificial Intelligence Research

In this paper, we present the partitioning of mutual-exclusion (mutex) constraints in temporal planning problems and its implementation in the SGPlan4 planner. Based on the strong locality of mutex constraints observed in many benchmarks of the Fourth International Planning Competition (IPC4), we propose to partition the constraints of a planning problem into groups based on their subgoals. Constraint partitioning leads to significantly easier subproblems that are similar to the original problem and that can be efficiently solved by the same planner with some modifications to its objective function. We present a partition-and-resolve strategy that looks for locally optimal subplans in constraint-partitioned temporal planning subproblems and that resolves those inconsistent global constraints across the subproblems. We also discuss some implementation details of SGPlan4, which include the resolution of violated global constraints, techniques for handling producible resources, landmark analysis, path finding and optimization, search-space reduction, and modifications of Metric-FF when used as a basic planner in SGPlan4. Last, we show results on the sensitivity of each of these techniques in quality-time trade-offs and experimentally demonstrate that SGPlan4 is effective for solving the IPC3 and IPC4 benchmarks.


Breaking Instance-Independent Symmetries In Exact Graph Coloring

Journal of Artificial Intelligence Research

Code optimization and high level synthesis can be posed as constraint satisfaction and optimization problems, such as graph coloring used in register allocation. Graph coloring is also used to model more traditional CSPs relevant to AI, such as planning, time-tabling and scheduling. Provably optimal solutions may be desirable for commercial and defense applications. Additionally, for applications such as register allocation and code optimization, naturally-occurring instances of graph coloring are often small and can be solved optimally. A recent wave of improvements in algorithms for Boolean satisfiability (SAT) and 0-1 Integer Linear Programming (ILP) suggests generic problem-reduction methods, rather than problem-specific heuristics, because (1) heuristics may be upset by new constraints, (2) heuristics tend to ignore structure, and (3) many relevant problems are provably inapproximable. Problem reductions often lead to highly symmetric SAT instances, and symmetries are known to slow down SAT solvers. In this work, we compare several avenues for symmetry breaking, in particular when certain kinds of symmetry are present in all generated instances. Our focus on reducing CSPs to SAT allows us to leverage recent dramatic improvement in SAT solvers and automatically benefit from future progress. We can use a variety of black-box SAT solvers without modifying their source code because our symmetry-breaking techniques are static, i.e., we detect symmetries and add symmetry breaking predicates (SBPs) during pre-processing. An important result of our work is that among the types of instance-independent SBPs we studied and their combinations, the simplest and least complete constructions are the most effective. Our experiments also clearly indicate that instance-independent symmetries should mostly be processed together with instance-specific symmetries rather than at the specification level, contrary to what has been suggested in the literature.


How the Landscape of Random Job Shop Scheduling Instances Depends on the Ratio of Jobs to Machines

Journal of Artificial Intelligence Research

We characterize the search landscape of random instances of the job shop scheduling problem (JSP). Specifically, we investigate how the expected values of (1) backbone size, (2) distance between near-optimal schedules, and (3) makespan of random schedules vary as a function of the job to machine ratio (N/M). For the limiting cases N/M approaches 0 and N/M approaches infinity we provide analytical results, while for intermediate values of N/M we perform experiments. We prove that as N/M approaches 0, backbone size approaches 100%, while as N/M approaches infinity the backbone vanishes. In the process we show that as N/M approaches 0 (resp. N/M approaches infinity), simple priority rules almost surely generate an optimal schedule, providing theoretical evidence of an "easy-hard-easy" pattern of typical-case instance difficulty in job shop scheduling. We also draw connections between our theoretical results and the "big valley" picture of JSP landscapes.