How to Deal with Unbelievable Assertions

We tackle the problem that arises when an agent receives unbelievable information. Information is unbelievable if it conflicts with the agent’s convictions, that is, what the agent considers knowledge. We propose two solutions based on modifying the information so that it is no longer unbelievable. In one solution, the source and the receiver of the information cooperatively resolve the conflict. For this purpose we introduce a dialogue protocol in which the receiver explains what is wrong with the information by using logical interpolation, and the source produces a new assertion accordingly. If such cooperation is not possible, we propose an alternative solution in which the receiver revises the new piece of information by its own convictions to make it acceptable.Peer reviewe

Towards a non monotonic description logics model

In order to deal with the Ontology Change problem and considering an environment where Description Logics (DLs) are used to describe ontologies, the question of how to integrate distributed ontologies appears to be in touch with Belief Revision since DL terminologies may define same concept descriptions of a not necessarily same world model. A possible alternative to reason about these concepts is to generate unique concept descriptions in a different terminology. This new terminology needs to be consistently created, trying to deal with the minimal change problem, and moreover, yielding a non-monotonic layer to express ontological knowledge in order to be further updated with new distributed ontologies.VII Workshop de Agentes y Sistemas Inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI

Efficient minimal preference change

In this article, we study a minimal change approach to preference dynamics. We treat a set of preferences as a special kind of theory, and define minimal change preference contraction and revision operations in the spirit of the Alchourrón, Gärdenfors, and Makinson theory of belief revision. We characterise minimal contraction of preference sets by a set of postulates and prove a representation theorem. We also give a linear time algorithm which implements minimal contraction by a single preference. We then define minimal contraction by a set of preferences, and show that the problem of a minimal contraction by a set of preferences is NP-hard

Proceedings of the IJCAI-09 Workshop on Nonmonotonic Reasoning, Action and Change

Copyright in each article is held by the authors. Please contact the authors directly for permission to reprint or use this material in any form for any purpose.The biennial workshop on Nonmonotonic Reasoning, Action and Change (NRAC) has an active and loyal community. Since its inception in 1995, the workshop has been held seven times in conjunction with IJCAI, and has experienced growing success. We hope to build on this success again this eighth year with an interesting and fruitful day of discussion. The areas of reasoning about action, non-monotonic reasoning and belief revision are among the most active research areas in Knowledge Representation, with rich inter-connections and practical applications including robotics, agentsystems, commonsense reasoning and the semantic web. This workshop provides a unique opportunity for researchers from all three fields to be brought together at a single forum with the prime objectives of communicating important recent advances in each field and the exchange of ideas. As these fundamental areas mature it is vital that researchers maintain a dialog through which they can cooperatively explore common links. The goal of this workshop is to work against the natural tendency of such rapidly advancing fields to drift apart into isolated islands of specialization. This year, we have accepted ten papers authored by a diverse international community. Each paper has been subject to careful peer review on the basis of innovation, significance and relevance to NRAC. The high quality selection of work could not have been achieved without the invaluable help of the international Program Committee. A highlight of the workshop will be our invited speaker Professor Hector Geffner from ICREA and UPF in Barcelona, Spain, discussing representation and inference in modern planning. Hector Geffner is a world leader in planning, reasoning, and knowledge representation; in addition to his many important publications, he is a Fellow of the AAAI, an associate editor of the Journal of Artificial Intelligence Research and won an ACM Distinguished Dissertation Award in 1990

Integración de ontologías Datalog+/-

En los últimos tiempos, la colaboración y el intercambio de información se han vuelto aspectos cruciales de muchos sistemas. En estos entornos es de vital importancia definir métodos automáticos para resolver conflictos entre el conocimiento compartido por distintos sistemas. Este conocimiento es frecuentemente expresado a través de ontologías que pueden ser compartidas por los sistemas que utilizan el mismo. En la presente investigación se busca la definición de métodos automáticos de integración de ontologías Datalog+/-. En base a lo logrado en este aspecto se buscará la adaptación del framework desarrollado para su aplicación tanto en la creación de federaciones de Bases de Datos (Data Federation) como en el intercambio de datos (Data Exchange). En estos campos de aplicación estos métodos podrán contribuir brindando la posibilidad de obtener de forma automática un esquema universal que respete tanto como sea posible a los originales manteniendo la coherencia del mismo con respecto a las restricciones de integridad impuestas a los datos, y definiendo que datos pueden ser mantenidos en la federación resolviendo incoherencias en el proceso. Adicionalmente, se analizarán posibles extensiones a Datalog+/- basadas en formalismos de Argumentación Rebatible, teniendo en cuenta aspectos como la definición on de relaciones de inferencia para estas ontologías aumentadas que tengan en cuenta los aspectos no-monótonos de la Argumentación Rebatible, o el impacto de tales relaciones en las conclusiones finales obtenidas y la complejidad de la obtención de las mismas.Eje: Agentes y Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Towards a non monotonic description logics model

In order to deal with the Ontology Change problem and considering an environment where Description Logics (DLs) are used to describe ontologies, the question of how to integrate distributed ontologies appears to be in touch with Belief Revision since DL terminologies may define same concept descriptions of a not necessarily same world model. A possible alternative to reason about these concepts is to generate unique concept descriptions in a different terminology. This new terminology needs to be consistently created, trying to deal with the minimal change problem, and moreover, yielding a non-monotonic layer to express ontological knowledge in order to be further updated with new distributed ontologies.VII Workshop de Agentes y Sistemas Inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI

Replacement of Hydrochlorofluorocarbon (HCFC) -225 Solvent for Cleaning and Verification Sampling of NASA Propulsion Oxygen Systems Hardware, Ground Support Equipment, and Associated Test Systems

Since the 1990's, NASA's rocket propulsion test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have used hydrochlorofluorocarbon-225 (HCFC-225), a Class II ozone-depleting substance, to safety clean and verify the cleanliness of large scale propulsion oxygen systems and associated test facilities. In 2012 through 2014, test laboratories at MSFC, SSC, and Johnson Space Center-White Sands Test Facility collaborated to seek out, test, and qualify an environmentally preferred replacement for HCFC-225. Candidate solvents were selected, a test plan was developed, and the products were tested for materials compatibility, oxygen compatibility, cleaning effectiveness, and suitability for use in cleanliness verification and field cleaning operations. Honewell Soltice (TradeMark) Performance Fluid (trans-1-chloro-3,3, 3-trifluoropropene) was selected to replace HCFC-225 at NASA's MSFC and SSC rocket propulsion test facilities

Fiction and Common Ground

The main aim of this dissertation is to model the different ways in which we use language when we engage with fiction. This main aim subdivides itself into a number of puzzles. We all know that dragons do not exist. Yet, when I read the Harry Potter novels, I do accept the existence of dragons. How do we keep such fictional truths separate from ‘ordinary’ non-fictional truths? What is the difference between Tolkien writing down all sorts of falsities, and a liar who also says all sorts of untrue things? How can it be true that Frodo was born in the Shire while it is also true that he was invented by Tolkien? Given that a fiction such as Pride and Prejudice is not about the actual world, how can I learn things about 19th century etiquette in England by reading this novel? I develop a coherent semantic analysis of these different puzzles: the ‘workspace account’. This theory is an extension of Stalnaker’s famous pragmatic ‘common ground’ framework. In this framework, assertions are modelled as proposals to update the ‘common ground’ (the set of shared assumptions) between conversational interlocutors