Doctor of Science, Washington University, Lic. en Matemática, U. Nac. del Sur. Chair LIDIA (AI Lab)Full Professor of Artificial Intelligence and Logic in Computer Science Dept. of Computer Science and Engineering, Universidad Nacional del Sur.Research interests: Knowledge Representation and Reasoning Computational, Logic, Logic Programming, Defeasible Reasoning, Belief Revision, Argumentation, Deliberate Systems, Autonomous Agents, Multi-Agent Systems.
Fue en 1956 cuando la "Dartmouth Summer Conference on Artificial Intelligence" acuñó el... more Fue en 1956 cuando la "Dartmouth Summer Conference on Artificial Intelligence" acuñó el término "Inteligencia Artificial". En esta conferencia se dieron cita un conjunto de investigadores interesados en la conjetura de que "todos los aspectos del aprendizaje o cualquier otra característica de la inteligencia pueden describirse en principio con tanta precisión como para hacer que una máquina los simule". Aún hoy día resulta interesante leer la propuesta original de esta reunión, que puede encontrarse en la página Web personal de John McCarthy, uno de ...
In this paper we present the DAQAP, a Web platform for Defeasible Argumentation Query Answering, ... more In this paper we present the DAQAP, a Web platform for Defeasible Argumentation Query Answering, which offers a visual interface that facilitates the analysis of the argumentative process defined in the Defeasible Logic Programming (DeLP) formalism. The tool presents graphs that show the interaction of the arguments generated from a DeLP program; this is done in two different ways: the first focuses on the structures obtained from the DeLP program, while the second presents the defeat relationships from the point of view of abstract argumentation frameworks, with the possibility of calculating the extensions using Dung’s semantics. Using all this data, the platform provides support for answering queries regarding the states of literals of the input program.
The following notes document in a succinct manner the use of the system PRODB. The system is stil... more The following notes document in a succinct manner the use of the system PRODB. The system is still evolving and several new features are in the process of being added. PRODB is a prototype system that is being used as an exploration vehicle of the possible extensions to the relational model through logic programming. The system consists of a relational database system having a relational algebra type language as a query language. It is written in Prolog and it extends the capabilities of Prolog predicates with the relational algebra operators for handling the database structure.
XI Congreso Argentino de Ciencias de la Computación, Oct 1, 2005
There are many areas in Computer Science where time plays an important role. Artificial Intellige... more There are many areas in Computer Science where time plays an important role. Artificial Intelligence is one of them. In this particular area Defeasible Logic Programming (DeLP) was developed to cope with incomplete and potentially inconsistent information. This formalism combines results from Logic Programming and Defeasible Argumentation. DeLP in particular provides the possibility of representing defeasible information in a declarative way and a defeasible argumentation inference mechanism to warrant conclusions. Although this formalism and Defeasible logic programming in general are very useful has left apart an issue that is crucial on several kind of problems, namely time. There are also many developments that face temporal reasoning, in particular Event Calculus, but non of them consider defeasible information or what to do if we have incomplete or not completely reliable information. In this work we try to attempt an exploration of a possible combination of these two reasoning areas, temporal and defeasible.
The technical report presents a succinct description of the Justification Finder (if). The system... more The technical report presents a succinct description of the Justification Finder (if). The system if is a practical implementation of the theoretical ideas introduced elsewhere (see the technical report "On the Logic of Defeasible Reasoning", G Simari, WUCS-89-12). It is used to explore and validate those ideas. The system provides support for defeasible reasoning in a Prolog environment. The complete Prolog language is available and only a few new predicates are introduced extending the reserved words of the language. We will present the theoretical underpinnings of the system in a very terse manner. The reader is referred to [1]... Read Read
We present a novel activating approach to Argument Theory Change (ATC) for the study of the dynam... more We present a novel activating approach to Argument Theory Change (ATC) for the study of the dynamics of the judicial process. ATC applies belief change concepts to dialectical argumentation for altering trees upon which the semantics for reasoning are defined. The activating approach to ATC considers the incorporation of arguments to define a revision operator for studying how to provoke change to the semantics’ outcome. Our objective is to contribute to the discussion of how to deal with circumstances of the judicial process like hypothetical reasoning for conducting investigations of a legal case, and for handling the dynamics of the judicial process. We finally observe the behavior of our proposal upon the sentences of two different real criminal procedures.
The Attack-Support Argumentation Framework (ASAF) is an abstract argumentation framework that pro... more The Attack-Support Argumentation Framework (ASAF) is an abstract argumentation framework that provides a unified setting for representing attack and support for arguments, as well as attack and support for the attack and support relations at any level. Currently, the extensions of the ASAF are obtained by translating it into a Dung's Argumentation Framework (AF). In this work we provide the ASAF with the ability of determining its extensions without requiring such a translation. We follow an extension-based approach for characterizing the acceptability semantics directly on the ASAF, considering the complete, preferred, stable and grounded semantics. Finally, we show that the proposed characterization satisfies different results from Dung's argumentation theory.
IV Congreso Argentina de Ciencias de la Computación, Nov 1, 1998
Desde comienzos de la década de los' 80 han aparecido un número significativo de for... more Desde comienzos de la década de los' 80 han aparecido un número significativo de formalismos que modelan, en ciertos aspéctos, el razonamiento de sentido común. El esfuerzo fué orientado a definir una clase de razonamiento que admitiese información incompleta y potencialmente inconsistente, fundamentalmente motivado por la intuición de que esta parece ser una característica distintiva de las decisiones tomadas por un agente inteligente. La plétora de sistemas ha generado un interés creciente por lograr criterios ...
XXV Congreso Argentino de Ciencias de la Computación (CACIC) (Universidad Nacional de Río Cuarto, Córdoba, 14 al 18 de octubre de 2019), 2019
Resumen. Este trabajo propone una metodología para evolucionar hacia un modelo educativo basado e... more Resumen. Este trabajo propone una metodología para evolucionar hacia un modelo educativo basado en competencias, partiendo de un plan de estudios estructurado por contenidos conceptuales, distribuidos en asignaturas. La metodología establece un conjunto genérico de competencias de egreso y captura la especificidad de cada carrera a partir de la definición de resultados del aprendizaje. La propuesta plantea la modificación
Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes ... more Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes of Multiagent Systems (MAS) and Distributed Artificial Intelligence (DAI). All of them authored by leading researchers of this dynamic multidisciplinary field.
Frontiers in artificial intelligence and applications, 2010
Models of argumentation often take a given set of rules or conditionals as a starting point. Argu... more Models of argumentation often take a given set of rules or conditionals as a starting point. Arguments to support or attack a position are then built from these rules. In this paper, an attempt is made to develop constraints on rules and their exceptions in such a way that they correspond exactly to arguments that successfully support their conclusions. The constraints take the form of properties of nonmonotonic consequence relations, similar to the ones that have been studied for cumulative inference.
As a practical mechanism for formalizing commonsense reasoning, argumentation has shown its poten... more As a practical mechanism for formalizing commonsense reasoning, argumentation has shown its potential for applications in diverse areas, many related to decision-making in knowledge-based systems. Following this line, and for helping users in making a better and informed decision, different recommender systems proposals have been developed in the argumentation literature. We will use recommender systems as a good example where to exercise our proposal. In particular, the role of preference criterion in argumentation-based recommender systems which is used to compare competing arguments is central to the user's query answering process where if the criterion does not adjust to the represented domain, the system could fail by being undecided too often. Therefore, having tools that allow to select and change the argument comparison mechanism has to be used become a central issue. Argumentation-based recommender systems that offer these tools provide an interesting ability that can be used for improving the reasoning capabilities in this type of systems. This work introduces an approach to handle multiple argument preference criteria in argumentation-based recommender systems and general knowledge-based decision support systems. More precisely, the proposal allows changing the information that a criterion can use in the argument comparison process and specify how several criteria can be simultaneously used in such process as well; to achieve that goal, a set of operators to combine several criteria is presented. The knowledge representation and reasoning is performed in Defeasible Logic Programming, a defeasible argumentation formalism based on logic programming.
Inteligencia Artificial,revista Iberoamericana De Inteligencia Artificial, 2013
Ontology merging refers to the process of creating a new ontology from two or more existing ontol... more Ontology merging refers to the process of creating a new ontology from two or more existing ontologies with overlapping parts. The δ-ontologies framework allows to reason with possibly inconsistent Description Logic ontologies by interpreting them in Defeasible Logic Programming, which is an approach to common-sense reasoning based on defeasible argumentation and logic programming. In traditional Description Logics, the knowledge expressed by a single ontology is separated into a terminological box and an assertional box. In contrast, in a δ-ontology, the terminological box is separated into an strict box (which must always be consistent) and a defeasible box (that could be inconsistent). Merging defeasible boxes is trivial but merging strict boxes is not since its union could result in an inconsistent strict box. In this article we extend the δ-ontologies framework by combining Argumentation, Belief Revision, and Description Logic ontologies to merge two ontologies such that the union of the strict terminologies could lead to inconsistency. We base our approach on a procedure presented by Falappa et al. where part of the inconsistent terminologies are turned defeasible by using a kernel revision operator applied to the set union of the ontologies. Resumen La mezcla de ontologías se refiere al proceso de creación de una nueva ontología a partir de dos más ontologías existentes con partes en común. El marco de las δ-ontologías permite razonar con ontologías en Lógica para la Descripción posiblemente inconsistentes al interpretarlas en Programación en Lógica Rebatible, la cual es un acercamiento al razonamiento de sentido común basado en argumentación rebatible y programación en lógica. En las Lógicas para la Descripción tradicionales, el conocimiento expresado por una ontología simple es separado en una caja terminológica y una caja asercional. En contraste, en una δ-ontología, la caja terminológica es separada en una caja estricta (que siempre debe ser consistente) y una caja rebatible (que podría ser inconsistente). Mezclar cajas rebatibles es trivial pero mezclar cajas estrictas no lo es puesto que tal unión podría resultar en una caja estricta inconsistente. En este artículo, extendemos el marco de las δ-ontologías al combinar Argumentación, Revisión de Creencias y Lógicas para la Descripción para mezclar dos ontologías tales que la unión de las terminologías estrictas podría llevar a inconsistencia. Basamos nuestro acercamiento en un procedimiento presentado por Falappa et al. donde parte de las terminologías inconsistentes son convertidas en rebatibles por medio de un operador de revisión de núcleo aplicado a la unión conjuntista de las ontologías.
Defeasible Logic Programming (DeLP) is an argumentation-based reasoning tool that allows users to... more Defeasible Logic Programming (DeLP) is an argumentation-based reasoning tool that allows users to contemplate reasons for and against certain conclusions---the warrant status of literals in the knowledge base is the main output of this dialectical process. Since the computation of these warrant statuses is a costly endeavor, any update to the knowledge base has a huge impact if carried out naively. In this paper, we study the case of updates consisting only of additions of either strict or defeasible rules, identifying conditions under which we can avoid wasted effort and proposing a data structure to keep track of which literals' warrant status can potentially be affected by a given update. We report the results of a preliminary set of experiments showing that our incremental algorithm affords significantly lower running times in practice.
Taking into account the increase in use of the multi-core cluster architecture, in this paper we ... more Taking into account the increase in use of the multi-core cluster architecture, in this paper we analyze the use of the various communication models (message passing, shared memory, their combination) to efficiently exploit the power of the architecture. Smith-Waterman algorithm, whose parallelization is based on a pipeline scheme due to problem data dependence, is used as test case to determine the similarity degree of two DNA sequences. Finally, future research lines are mentioned, aimed at optimizing the use of memory levels in the architecture.
Fue en 1956 cuando la "Dartmouth Summer Conference on Artificial Intelligence" acuñó el... more Fue en 1956 cuando la "Dartmouth Summer Conference on Artificial Intelligence" acuñó el término "Inteligencia Artificial". En esta conferencia se dieron cita un conjunto de investigadores interesados en la conjetura de que "todos los aspectos del aprendizaje o cualquier otra característica de la inteligencia pueden describirse en principio con tanta precisión como para hacer que una máquina los simule". Aún hoy día resulta interesante leer la propuesta original de esta reunión, que puede encontrarse en la página Web personal de John McCarthy, uno de ...
In this paper we present the DAQAP, a Web platform for Defeasible Argumentation Query Answering, ... more In this paper we present the DAQAP, a Web platform for Defeasible Argumentation Query Answering, which offers a visual interface that facilitates the analysis of the argumentative process defined in the Defeasible Logic Programming (DeLP) formalism. The tool presents graphs that show the interaction of the arguments generated from a DeLP program; this is done in two different ways: the first focuses on the structures obtained from the DeLP program, while the second presents the defeat relationships from the point of view of abstract argumentation frameworks, with the possibility of calculating the extensions using Dung’s semantics. Using all this data, the platform provides support for answering queries regarding the states of literals of the input program.
The following notes document in a succinct manner the use of the system PRODB. The system is stil... more The following notes document in a succinct manner the use of the system PRODB. The system is still evolving and several new features are in the process of being added. PRODB is a prototype system that is being used as an exploration vehicle of the possible extensions to the relational model through logic programming. The system consists of a relational database system having a relational algebra type language as a query language. It is written in Prolog and it extends the capabilities of Prolog predicates with the relational algebra operators for handling the database structure.
XI Congreso Argentino de Ciencias de la Computación, Oct 1, 2005
There are many areas in Computer Science where time plays an important role. Artificial Intellige... more There are many areas in Computer Science where time plays an important role. Artificial Intelligence is one of them. In this particular area Defeasible Logic Programming (DeLP) was developed to cope with incomplete and potentially inconsistent information. This formalism combines results from Logic Programming and Defeasible Argumentation. DeLP in particular provides the possibility of representing defeasible information in a declarative way and a defeasible argumentation inference mechanism to warrant conclusions. Although this formalism and Defeasible logic programming in general are very useful has left apart an issue that is crucial on several kind of problems, namely time. There are also many developments that face temporal reasoning, in particular Event Calculus, but non of them consider defeasible information or what to do if we have incomplete or not completely reliable information. In this work we try to attempt an exploration of a possible combination of these two reasoning areas, temporal and defeasible.
The technical report presents a succinct description of the Justification Finder (if). The system... more The technical report presents a succinct description of the Justification Finder (if). The system if is a practical implementation of the theoretical ideas introduced elsewhere (see the technical report "On the Logic of Defeasible Reasoning", G Simari, WUCS-89-12). It is used to explore and validate those ideas. The system provides support for defeasible reasoning in a Prolog environment. The complete Prolog language is available and only a few new predicates are introduced extending the reserved words of the language. We will present the theoretical underpinnings of the system in a very terse manner. The reader is referred to [1]... Read Read
We present a novel activating approach to Argument Theory Change (ATC) for the study of the dynam... more We present a novel activating approach to Argument Theory Change (ATC) for the study of the dynamics of the judicial process. ATC applies belief change concepts to dialectical argumentation for altering trees upon which the semantics for reasoning are defined. The activating approach to ATC considers the incorporation of arguments to define a revision operator for studying how to provoke change to the semantics’ outcome. Our objective is to contribute to the discussion of how to deal with circumstances of the judicial process like hypothetical reasoning for conducting investigations of a legal case, and for handling the dynamics of the judicial process. We finally observe the behavior of our proposal upon the sentences of two different real criminal procedures.
The Attack-Support Argumentation Framework (ASAF) is an abstract argumentation framework that pro... more The Attack-Support Argumentation Framework (ASAF) is an abstract argumentation framework that provides a unified setting for representing attack and support for arguments, as well as attack and support for the attack and support relations at any level. Currently, the extensions of the ASAF are obtained by translating it into a Dung's Argumentation Framework (AF). In this work we provide the ASAF with the ability of determining its extensions without requiring such a translation. We follow an extension-based approach for characterizing the acceptability semantics directly on the ASAF, considering the complete, preferred, stable and grounded semantics. Finally, we show that the proposed characterization satisfies different results from Dung's argumentation theory.
IV Congreso Argentina de Ciencias de la Computación, Nov 1, 1998
Desde comienzos de la década de los' 80 han aparecido un número significativo de for... more Desde comienzos de la década de los' 80 han aparecido un número significativo de formalismos que modelan, en ciertos aspéctos, el razonamiento de sentido común. El esfuerzo fué orientado a definir una clase de razonamiento que admitiese información incompleta y potencialmente inconsistente, fundamentalmente motivado por la intuición de que esta parece ser una característica distintiva de las decisiones tomadas por un agente inteligente. La plétora de sistemas ha generado un interés creciente por lograr criterios ...
XXV Congreso Argentino de Ciencias de la Computación (CACIC) (Universidad Nacional de Río Cuarto, Córdoba, 14 al 18 de octubre de 2019), 2019
Resumen. Este trabajo propone una metodología para evolucionar hacia un modelo educativo basado e... more Resumen. Este trabajo propone una metodología para evolucionar hacia un modelo educativo basado en competencias, partiendo de un plan de estudios estructurado por contenidos conceptuales, distribuidos en asignaturas. La metodología establece un conjunto genérico de competencias de egreso y captura la especificidad de cada carrera a partir de la definición de resultados del aprendizaje. La propuesta plantea la modificación
Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes ... more Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes of Multiagent Systems (MAS) and Distributed Artificial Intelligence (DAI). All of them authored by leading researchers of this dynamic multidisciplinary field.
Frontiers in artificial intelligence and applications, 2010
Models of argumentation often take a given set of rules or conditionals as a starting point. Argu... more Models of argumentation often take a given set of rules or conditionals as a starting point. Arguments to support or attack a position are then built from these rules. In this paper, an attempt is made to develop constraints on rules and their exceptions in such a way that they correspond exactly to arguments that successfully support their conclusions. The constraints take the form of properties of nonmonotonic consequence relations, similar to the ones that have been studied for cumulative inference.
As a practical mechanism for formalizing commonsense reasoning, argumentation has shown its poten... more As a practical mechanism for formalizing commonsense reasoning, argumentation has shown its potential for applications in diverse areas, many related to decision-making in knowledge-based systems. Following this line, and for helping users in making a better and informed decision, different recommender systems proposals have been developed in the argumentation literature. We will use recommender systems as a good example where to exercise our proposal. In particular, the role of preference criterion in argumentation-based recommender systems which is used to compare competing arguments is central to the user's query answering process where if the criterion does not adjust to the represented domain, the system could fail by being undecided too often. Therefore, having tools that allow to select and change the argument comparison mechanism has to be used become a central issue. Argumentation-based recommender systems that offer these tools provide an interesting ability that can be used for improving the reasoning capabilities in this type of systems. This work introduces an approach to handle multiple argument preference criteria in argumentation-based recommender systems and general knowledge-based decision support systems. More precisely, the proposal allows changing the information that a criterion can use in the argument comparison process and specify how several criteria can be simultaneously used in such process as well; to achieve that goal, a set of operators to combine several criteria is presented. The knowledge representation and reasoning is performed in Defeasible Logic Programming, a defeasible argumentation formalism based on logic programming.
Inteligencia Artificial,revista Iberoamericana De Inteligencia Artificial, 2013
Ontology merging refers to the process of creating a new ontology from two or more existing ontol... more Ontology merging refers to the process of creating a new ontology from two or more existing ontologies with overlapping parts. The δ-ontologies framework allows to reason with possibly inconsistent Description Logic ontologies by interpreting them in Defeasible Logic Programming, which is an approach to common-sense reasoning based on defeasible argumentation and logic programming. In traditional Description Logics, the knowledge expressed by a single ontology is separated into a terminological box and an assertional box. In contrast, in a δ-ontology, the terminological box is separated into an strict box (which must always be consistent) and a defeasible box (that could be inconsistent). Merging defeasible boxes is trivial but merging strict boxes is not since its union could result in an inconsistent strict box. In this article we extend the δ-ontologies framework by combining Argumentation, Belief Revision, and Description Logic ontologies to merge two ontologies such that the union of the strict terminologies could lead to inconsistency. We base our approach on a procedure presented by Falappa et al. where part of the inconsistent terminologies are turned defeasible by using a kernel revision operator applied to the set union of the ontologies. Resumen La mezcla de ontologías se refiere al proceso de creación de una nueva ontología a partir de dos más ontologías existentes con partes en común. El marco de las δ-ontologías permite razonar con ontologías en Lógica para la Descripción posiblemente inconsistentes al interpretarlas en Programación en Lógica Rebatible, la cual es un acercamiento al razonamiento de sentido común basado en argumentación rebatible y programación en lógica. En las Lógicas para la Descripción tradicionales, el conocimiento expresado por una ontología simple es separado en una caja terminológica y una caja asercional. En contraste, en una δ-ontología, la caja terminológica es separada en una caja estricta (que siempre debe ser consistente) y una caja rebatible (que podría ser inconsistente). Mezclar cajas rebatibles es trivial pero mezclar cajas estrictas no lo es puesto que tal unión podría resultar en una caja estricta inconsistente. En este artículo, extendemos el marco de las δ-ontologías al combinar Argumentación, Revisión de Creencias y Lógicas para la Descripción para mezclar dos ontologías tales que la unión de las terminologías estrictas podría llevar a inconsistencia. Basamos nuestro acercamiento en un procedimiento presentado por Falappa et al. donde parte de las terminologías inconsistentes son convertidas en rebatibles por medio de un operador de revisión de núcleo aplicado a la unión conjuntista de las ontologías.
Defeasible Logic Programming (DeLP) is an argumentation-based reasoning tool that allows users to... more Defeasible Logic Programming (DeLP) is an argumentation-based reasoning tool that allows users to contemplate reasons for and against certain conclusions---the warrant status of literals in the knowledge base is the main output of this dialectical process. Since the computation of these warrant statuses is a costly endeavor, any update to the knowledge base has a huge impact if carried out naively. In this paper, we study the case of updates consisting only of additions of either strict or defeasible rules, identifying conditions under which we can avoid wasted effort and proposing a data structure to keep track of which literals' warrant status can potentially be affected by a given update. We report the results of a preliminary set of experiments showing that our incremental algorithm affords significantly lower running times in practice.
Taking into account the increase in use of the multi-core cluster architecture, in this paper we ... more Taking into account the increase in use of the multi-core cluster architecture, in this paper we analyze the use of the various communication models (message passing, shared memory, their combination) to efficiently exploit the power of the architecture. Smith-Waterman algorithm, whose parallelization is based on a pipeline scheme due to problem data dependence, is used as test case to determine the similarity degree of two DNA sequences. Finally, future research lines are mentioned, aimed at optimizing the use of memory levels in the architecture.
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Papers by Guillermo R. Simari