Technology
Diagnosis as Planning Revisited
Sohrabi, Shirin (University of Toronto) | Baier, Jorge A. (Departamento de Ciencia de la Computacion Universidad Catolica de Chile) | McIlraith, Sheila A. (University of Toronto)
In discrete dynamical systems change results from actions. As such, given a set of observations, diagnoses often take the form of posited events that result in the observed behaviour. In this paper we revisit formal characterizations of diagnosis, and their relationship to planning. We do so from both a theoretical and a computational perspective. In particular, we extend the characterization of diagnosis to deal with the case of incomplete information, and rich preferences. We also explore the use of state-of-the-art planning technology for the automated generation of diagnoses. Examining several classes of diagnosis problems, we provide both proof of concept and benchmark experiments, the latter showing superior performance to a leading diagnosis engine. Our findings help support the hypothesis that planning technology holds great promise for efficient generation of diagnoses.
New Advances in Sequential Diagnosis
Siddiqi, Sajjad Ahmed (National University of Sciences and Technologies) | Huang, Jinbo (NICTA and Australian National University)
Sequential diagnosis takes measurements of an abnormal system to identify faulty components, where the goal is to reduce the diagnostic cost , defined here as the number of measurements. To propose measurement points, previous work employs a heuristic based on reducing the entropy over a set of diagnoses , which can be impractical when the set of diagnoses is too large. Focusing on a smaller set of probable diagnoses scales the approach but generally leads to increased diagnostic cost. We propose a new diagnostic framework employing three new techniques — a more efficient heuristic for measurement point selection, abstraction-based sequential diagnosis, and component cloning — which scales to large systems with good performance in terms of diagnostic cost.
Complexity of Propositional Abduction for Restricted Sets of Boolean Functions
Creignou, Nadia (Université d'Aix-Marseille II) | Schmidt, Johannes (Université d'Aix-Marseille II) | Thomas, Michael (Leibniz Universität Hannover)
Abduction is a fundamental and important form of non-monotonic reasoning. Given a knowledge base explaining how the world behaves it aims at finding an explanation for some observed manifestation. In this paper we focus on propositional abduction, where the knowledge base and the manifestation are represented by propositional formulae. The problem of deciding whether there exists an explanation has been shown to be Σ p 2 -complete in general. We consider variants obtained by restricting the allowed connectives in the formulae to certain sets of Boolean functions. We give a complete classification of the complexity for all considerable sets of Boolean functions. In this way, we identify easier cases, namely NP-complete and polynomial cases; and we highlight sources of intractability. Further, we address the problem of counting the explanations and draw a complete picture for the counting complexity.
Tutorial Presentations at the Twelfth International Conference on Principles of Knowledge Representation and Reasoning
Moura, Leonardo de (Microsoft Research) | Lutz, Carsten (University of Bremen) | Schraefel, Monica Mc (University of Southampton) | Nebel, Bernhard (University of Freiburg)
In particular, I will explain how the complexity scheduling, planning, graph problems, among others. The landscape differs for traditional reasoning and for query most well-known constraint satisfaction problem is propositional answering, and take a brief look at computational complexity satisfiability SAT. Of particular recent interest is satisfiability issues raised by implementations of DL query answering modulo theories (SMT), where the interpretation based on standard relational database systems. Throughout of some symbols is constrained by a background theory. For the tutorial, connections to the W3C-standard OWL are example, the theory of arithmetic restricts the interpretation drawn whenever possible. of symbols such as:,, 0, and 1. SMT draws on the most prolific problems in the past century What If You Wanted Someone (Else) to Use This?
Reasoning about Actions and Change: From Single Agent Actions to Multi-Agent Actions (Extended Abstract)
Baral, Chitta (Arizona State University)
We often deal with dynamic worlds where actions are executed by agents and events may happen. Example of such worlds range from virtual worlds such as the world of a database to robots and humans in physical worlds. To understand the dynamics of such worlds as well as to be able to assert some control over such worlds one needs to reason about the actions and events and how they may change the world. In this invited talk we will present some of the important results in this field and present some future directions. In particular, we will discuss how theories and results from reasoning about actions and change can be combined with theories and results in dynamic epistemic logics to obtain a unified theory of multi-agent actions.
Invited Presentations at the Twelfth International Conference on Principles of Knowledge Representation and Reasoning
Baral, Chitta (Arizona State University) | Horrocks, Ian (Oxford University) | Shoham, Yoav (Stanford University)
Invited Talk by Ian Horrocks Ontologies and ontology based systems are rapidly becoming mainstream technologies, with RDF and OWL now being deployed in diverse application domains, and with major technology vendors starting to augment their existing systems with ontological reasoning. For example, Oracle Inc. recently enhanced its well-known database management system with modules that use RDF/OWL ontologies to support "semantic data management," and their product brochure lists numerous application areas that can benefit from this technology, including enterprise information integration, knowledge mining, finance, compliance management and life science research. While gratifying to the KR research community, this success also brings with it many challenges. In particular, ontology reasoning systems will need to exhibit robust scalability if deployments in large scale applications are to be successful.
Improving the Johnson-Lindenstrauss Lemma
The Johnson-Lindenstrauss Lemma allows for the projection of $n$ points in $p-$dimensional Euclidean space onto a $k-$dimensional Euclidean space, with $k \ge \frac{24\ln \emph{n}}{3\epsilon^2-2\epsilon^3}$, so that the pairwise distances are preserved within a factor of $1\pm\epsilon$. Here, working directly with the distributions of the random distances rather than resorting to the moment generating function technique, an improvement on the lower bound for $k$ is obtained. The additional reduction in dimension when compared to bounds found in the literature, is at least $13\%$, and, in some cases, up to $30\%$ additional reduction is achieved. Using the moment generating function technique, we further provide a lower bound for $k$ using pairwise $L_2$ distances in the space of points to be projected and pairwise $L_1$ distances in the space of the projected points. Comparison with the results obtained in the literature shows that the bound presented here provides an additional $36-40\%$ reduction.
ECG Feature Extraction Techniques - A Survey Approach
Karpagachelvi, S., Arthanari, M., Sivakumar, M.
ECG Feature Extraction plays a significant role in diagnosing most of the cardiac diseases. One cardiac cycle in an ECG signal consists of the P-QRS-T waves. This feature extraction scheme determines the amplitudes and intervals in the ECG signal for subsequent analysis. The amplitudes and intervals value of P-QRS-T segment determines the functioning of heart of every human. Recently, numerous research and techniques have been developed for analyzing the ECG signal. The proposed schemes were mostly based on Fuzzy Logic Methods, Artificial Neural Networks (ANN), Genetic Algorithm (GA), Support Vector Machines (SVM), and other Signal Analysis techniques. All these techniques and algorithms have their advantages and limitations. This proposed paper discusses various techniques and transformations proposed earlier in literature for extracting feature from an ECG signal. In addition this paper also provides a comparative study of various methods proposed by researchers in extracting the feature from ECG signal.
On Building a Knowledge Base for Stability Theory
Rowinska-Schwarzweller, Agnieszka, Schwarzweller, Christoph
A lot of mathematical knowledge has been formalized and stored in repositories by now: different mathematical theorems and theories have been taken into consideration and included in mathematical repositories. Applications more distant from pure mathematics, however --- though based on these theories --- often need more detailed knowledge about the underlying theories. In this paper we present an example Mizar formalization from the area of electrical engineering focusing on stability theory which is based on complex analysis. We discuss what kind of special knowledge is necessary here and which amount of this knowledge is included in existing repositories.
A two-step fusion process for multi-criteria decision applied to natural hazards in mountains
Tacnet, Jean-Marc, Batton-Hubert, Mireille, Dezert, Jean
Mountain river torrents and snow avalanches generate human and material damages with dramatic consequences. Knowledge about natural phenomenona is often lacking and expertise is required for decision and risk management purposes using multi-disciplinary quantitative or qualitative approaches. Expertise is considered as a decision process based on imperfect information coming from more or less reliable and conflicting sources. A methodology mixing the Analytic Hierarchy Process (AHP), a multi-criteria aid-decision method, and information fusion using Belief Function Theory is described. Fuzzy Sets and Possibilities theories allow to transform quantitative and qualitative criteria into a common frame of discernment for decision in Dempster-Shafer Theory (DST ) and Dezert-Smarandache Theory (DSmT) contexts. Main issues consist in basic belief assignments elicitation, conflict identification and management, fusion rule choices, results validation but also in specific needs to make a difference between importance and reliability and uncertainty in the fusion process.