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Guillermo R. Simari [17]Guillermo Ricardo Simari [7]
  1.  17
    A mathematical treatment of defeasible reasoning and its implementation.Guillermo R. Simari & Ronald P. Loui - 1992 - Artificial Intelligence 53 (2-3):125-157.
    We present a mathematical approach to defeasible reasoning based on arguments. This approach integrates the notion of specificity introduced by Poole and the theory of warrant presented by Pollock. The main contribution of this paper is a precise, well-defined system which exhibits correct behavior when applied to the benchmark examples in the literature. It aims for usability rather than novelty. We prove that an order relation can be introduced among equivalence classes of arguments under the equi-specificity relation. We also prove (...)
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  2.  25
    Defeasible logic programming: DeLP-servers, contextual queries, and explanations for answers.Alejandro J. García & Guillermo R. Simari - 2014 - Argument and Computation 5 (1):63-88.
    Argumentation represents a way of reasoning over a knowledge base containing possibly incomplete and/or inconsistent information, to obtain useful conclusions. As a reasoning mechanism, the way an argumentation reasoning engine reaches these conclusions resembles the cognitive process that humans follow to analyze their beliefs; thus, unlike other computationally reasoning systems, argumentation offers an intellectually friendly alternative to other defeasible reasoning systems. LogicProgrammingisacomputationalparadigmthathasproducedcompu- tationallyattractivesystemswithremarkablesuccessinmanyapplications. Merging ideas from both areas, Defeasible Logic Programming offers a computational reasoning system that uses an argumentation engine (...)
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  3.  9
    Prioritized and Non-prioritized Multiple Change on Belief Bases.Marcelo A. Falappa, Gabriele Kern-Isberner, Maurício D. L. Reis & Guillermo R. Simari - 2012 - Journal of Philosophical Logic 41 (1):77-113.
    In this article we explore multiple change operators, i.e., operators in which the epistemic input is a set of sentences instead of a single sentence. We propose two types of change: prioritized change, in which the input set is fully accepted, and symmetric change, where both the epistemic state and the epistemic input are equally treated. In both kinds of operators we propose a set of postulates and we present different constructions: kernel changes and partial meet changes.
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  4.  17
    Arguing about informant credibility in open multi-agent systems.Sebastian Gottifredi, Luciano H. Tamargo, Alejandro J. García & Guillermo R. Simari - 2018 - Artificial Intelligence 259 (C):91-109.
    This paper proposes the use of an argumentation framework with recursive attacks to address a trust model in a collaborative open multi-agent system. Our approach is focused on scenarios where agents share information about the credibility (informational trust) they have assigned to their peers. We will represent informants’ credibility through credibility objects which will include not only trust information but also the informant source. This leads to a recursive setting where the reliability of certain credibility information depends on the credibility (...)
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  5.  14
    On the revision of informant credibility orders.Luciano H. Tamargo, Alejandro J. García, Marcelo A. Falappa & Guillermo R. Simari - 2014 - Artificial Intelligence 212 (C):36-58.
    In this paper we propose an approach to multi-source belief revision where the trust or credibility assigned to informant agents can be revised. In our proposal, the credibility of each informant represented as a strict partial order among informant agents, will be maintained in a repository called credibility base. Upon arrival of new information concerning the credibility of its peers, an agent will be capable of revising this strict partial order, changing the trust assigned to its peers accordingly. Our goal (...)
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  6.  10
    Explanations, belief revision and defeasible reasoning.Marcelo A. Falappa, Gabriele Kern-Isberner & Guillermo R. Simari - 2002 - Artificial Intelligence 141 (1-2):1-28.
    We present different constructions for nonprioritized belief revision, that is, belief changes in which the input sentences are not always accepted. First, we present the concept of explanation in a deductive way. Second, we define multiple revision operators with respect to sets of sentences (representing explanations), giving representation theorems. Finally, we relate the formulated operators with argumentative systems and default reasoning frameworks.
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  7.  24
    An approach to abstract argumentation with recursive attack and support.Andrea Cohen, Sebastian Gottifredi, Alejandro J. García & Guillermo R. Simari - 2015 - Journal of Applied Logic 13 (4):509-533.
    This work introduces the Attack-Support Argumentation Framework (ASAF), an approach to abstract argumentation that allows for the representation and combination of attack and support relations. This framework extends the argumentation Framework with Recursive Attacks (AFRA) in two ways. Firstly, it adds a support relation enabling to express support for arguments; this support can also be given to attacks, and to the support relation itself. Secondly, it extends AFRA’s attack relation by allowing attacks to the aforementioned support relation. Moreover, since the (...)
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  8.  44
    Belief Revision and Computational Argumentation: A Critical Comparison.Pietro Baroni, Eduardo Fermé, Massimiliano Giacomin & Guillermo Ricardo Simari - 2022 - Journal of Logic, Language and Information 31 (4):555-589.
    This paper aims at comparing and relating belief revision and argumentation as approaches to model reasoning processes. Referring to some prominent literature references in both fields, we will discuss their (implicit or explicit) assumptions on the modeled processes and hence commonalities and differences in the forms of reasoning they are suitable to deal with. The intended contribution is on one hand assessing the (not fully explored yet) relationships between two lively research fields in the broad area of defeasible reasoning and (...)
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  9.  18
    An approach to decision making based on dynamic argumentation systems.Edgardo Ferretti, Luciano H. Tamargo, Alejandro J. García, Marcelo L. Errecalde & Guillermo R. Simari - 2017 - Artificial Intelligence 242 (C):107-131.
    In this paper we introduce a formalism for single-agent decision making that is based on Dynamic Argumentation Frameworks. The formalism can be used to justify a choice, which is based on the current situation the agent is involved. Taking advantage of the inference mechanism of the argumentation formalism, it is possible to consider preference relations, and conflicts among the available alternatives for that reasoning. With this formalization, given a particular set of evidence, the justified conclusions supported by warranted arguments will (...)
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  10.  39
    Similarity notions in bipolar abstract argumentation.Paola Daniela Budán, Melisa Gisselle Escañuela Gonzalez, Maximiliano Celmo David Budán, Maria Vanina Martinez & Guillermo Ricardo Simari - 2020 - Argument and Computation 11 (1-2):103-149.
    Abstract. The notion of similarity has been studied in many areas of Computer Science; in a general sense, this concept is defined to provide a measure of the semantic equivalence between two pieces of knowledge, expressing how “close” their meaning can be regarded. In this work, we study similarity as a tool useful to improve the representation of arguments, the interpretation of the relations between arguments, and the semantic evaluation associated with the arguments in the argumentative process. In this direction, (...)
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  11.  20
    Stratified Belief Bases Revision with Argumentative Inference.Marcelo Alejandro Falappa, Alejandro Javier García, Gabriele Kern-Isberner & Guillermo Ricardo Simari - 2013 - Journal of Philosophical Logic 42 (1):161-193.
    We propose a revision operator on a stratified belief base, i.e., a belief base that stores beliefs in different strata corresponding to the value an agent assigns to these beliefs. Furthermore, the operator will be defined as to perform the revision in such a way that information is never lost upon revision but stored in a stratum or layer containing information perceived as having a lower value. In this manner, if the revision of one layer leads to the rejection of (...)
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  12.  22
    Incremental computation for structured argumentation over dynamic DeLP knowledge bases.Gianvincenzo Alfano, Sergio Greco, Francesco Parisi, Gerardo I. Simari & Guillermo R. Simari - 2021 - Artificial Intelligence 300 (C):103553.
    Structured argumentation systems, and their implementation, represent an important research subject in the area of Knowledge Representation and Reasoning. Structured argumentation advances over abstract argumentation frameworks by providing the internal construction of the arguments that are usually defined by a set of (strict and defeasible) rules. By considering the structure of arguments, it becomes possible to analyze reasons for and against a conclusion, and the warrant status of such a claim in the context of a knowledge base represents the main (...)
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  13.  17
    An informant-based approach to argument strength in Defeasible Logic Programming.Andrea Cohen, Sebastian Gottifredi, Luciano H. Tamargo, Alejandro J. García & Guillermo R. Simari - 2021 - Argument and Computation 12 (1):115-147.
    This work formalizes an informant-based structured argumentation approach in a multi-agent setting, where the knowledge base of an agent may include information provided by other agents, and each piece of knowledge comes attached with its informant. In that way, arguments are associated with the set of informants corresponding to the information they are built upon. Our approach proposes an informant-based notion of argument strength, where the strength of an argument is determined by the credibility of its informant agents. Moreover, we (...)
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  14.  12
    Characterizing acceptability semantics of argumentation frameworks with recursive attack and support relations.Sebastian Gottifredi, Andrea Cohen, Alejandro J. García & Guillermo R. Simari - 2018 - Artificial Intelligence 262 (C):336-368.
    Over the last decade, several extensions of Dung’s Abstract Argumentation Frameworks (AFs) have been introduced in the literature. Some of these extensions concern the nature of the attack relation, such as the consideration of recursive attacks, whereas others incorporate additional interactions, such as a support relation. Recently, the Attack–Support Argumentation Framework (ASAF) was proposed, which accounts for recursive attacks and supports, attacks to supports and supports to attacks, at any level, where the support relation is interpreted as necessity. Currently, to (...)
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  15.  21
    A labeled argumentation framework.Maximiliano C. D. Budán, Mauro Gómez Lucero, Ignacio Viglizzo & Guillermo R. Simari - 2015 - Journal of Applied Logic 13 (4):534-553.
    Argumentation is a form of reasoning where a claim is accepted or rejected according to the analysis of the arguments for and against it; furthermore, it provides a reasoning mechanism able to handle contradictory, incomplete and uncertain information in real-world situations. We combine Bipolar Argumentation Frameworks (an extension of Dung’s work) with an Algebra of Argumentation Labels modeling two independent types of interaction between arguments, representing meta-information associated with arguments, and introducing an acceptability notion that will give more information for (...)
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  16.  18
    Belief base contraction by belief accrual.Cristhian A. D. Deagustini, M. Vanina Martinez, Marcelo A. Falappa & Guillermo R. Simari - 2019 - Artificial Intelligence 275 (C):78-103.
    The problem of knowledge evolution has received considerable attention over the years. Mainly, the study of the dynamics of knowledge has been addressed in the area of Belief Revision, a field emerging as the convergence of the efforts in Philosophy, Logic, and more recently Computer Science, where research efforts usually involve “flat” knowledge bases where there is no additional information about the formulas stored in it. Even when this may be a good fit for particular applications, in many real-world scenarios (...)
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  17.  8
    Credulous acceptance in high-order argumentation frameworks with necessities: An incremental approach.Gianvincenzo Alfano, Andrea Cohen, Sebastian Gottifredi, Sergio Greco, Francesco Parisi & Guillermo R. Simari - 2024 - Artificial Intelligence 333 (C):104159.
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  18. Defeasible argumentation over relational databases.Cristhian Ariel David Deagustini, Santiago Emanuel Fulladoza Dalibón, Sebastián Gottifredi, Marcelo Alejandro Falappa, Carlos Iván Chesñevar & Guillermo Ricardo Simari - 2017 - Argument and Computation 8 (1):35-59.
    Defeasible argumentation has been applied successfully in several real-world domains in which it is necessary to handle incomplete and contradictory information. In recent years, there have been interesting attempts to carry out argumentation processes supported by massive repositories developing argumentative reasoning applications. One of such efforts builds arguments by retrieving information from relational databases using the DBI-DeLP framework; this article presents eDBI-DeLP, which extends the original DBI-DeLP framework by providing two novel aspects which refine the interaction between DeLP programs and (...)
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  19. Computing Generalized Specificity.Frieder Stolzenberg, Alejandro Javier Garcia, Carlos Ivan Chesñevar & Guillermo Ricardo Simari - 2003 - Journal of Applied Non-Classical Logics 13 (1):87-113.
    Most formalisms for representing common-sense knowledge allow incomplete and potentially inconsistent information. When strong negation is also allowed, contradictory conclusions can arise. A criterion for deciding between them is needed. The aim of this paper is to investigate an inherent and autonomous comparison criterion, based on specificity as defined in [POO 85, SIM 92]. In contrast to other approaches, we consider not only defeasible, but also strict knowledge. Our criterion is context-sensitive, i. e., preference among defeasible rules is determined dynamically (...)
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  20.  12
    Merging operators on stratified belief bases equipped with argumentative inference.Marcelo A. Falappa, Alejandro J. García & Guillermo R. Simari - 2023 - Journal of Applied Non-Classical Logics 33 (3-4):387-420.
    This work considers the formalisation of the merging process of stratified belief bases, where beliefs are stored in different layers or strata. Their strata are ranked, following a total order, employing the value the agent using the belief base assigns to these beliefs. The agent uses an argumentation mechanism to reason from the belief base and obtain the final inferences. We present two ways of merging stratified belief bases: the first is defined by merging two strata without belief preservation, and (...)
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  21.  89
    Introducing Argument & Computation.Guillermo R. Simari, Chris Reed, Iyad Rahwan & Floriana Grasso - 2010 - Argument and Computation 1 (1):1-5.
    Over the past decade or so, a new interdisciplinary field has emerged in the ground between, on the one hand, computer science – and artificial intelligence in particular – and, on the other, the area of philosophy concentrating on the language and structure of argument. There are now hundreds of researchers worldwide who would consider themselves a part of this nascent community. Various terms have been proposed for the area, including "Computational Dialectics," "Argumentation Technology," and "Argument-based Computing," but the term (...)
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  22.  11
    Computing Generalized Specificity.Frieder Stolzenburg, Alejandro J. García, Carlos I. Chesñevar & Guillermo R. Simari - 2003 - Journal of Applied Non-Classical Logics 13 (1):87-113.
    Most formalisms for representing common-sense knowledge allow incomplete and potentially inconsistent information. When strong negation is also allowed, contradictory conclusions can arise. A criterion for deciding between them is needed. The aim of this paper is to investigate an inherent and autonomous comparison criterion, based on specificity as defined in [POO 85, SIM 92]. In contrast to other approaches, we consider not only defeasible, but also strict knowledge. Our criterion is context-sensitive, i. e., preference among defeasible rules is determined dynamically (...)
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  23.  11
    Strength in coalitions: Community detection through argument similarity.Paola Daniela Budán, Melisa Gisselle Escañuela Gonzalez, Maximiliano Celmo David Budán, Maria Vanina Martinez & Guillermo Ricardo Simari - 2023 - Argument and Computation 14 (3):275-325.
    We present a novel argumentation-based method for finding and analyzing communities in social media on the Web, where a community is regarded as a set of supported opinions that might be in conflict. Based on their stance, we identify argumentative coalitions to define them; then, we apply a similarity-based evaluation method over the set of arguments in the coalition to determine the level of cohesion inherent to each community, classifying them appropriately. Introducing conflict points and attacks between coalitions based on (...)
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  24.  11
    Modelling inference in argumentation through labelled deduction: Formalization and logical properties. [REVIEW]Carlos Iván Chesñevar & Guillermo Ricardo Simari - 2007 - Logica Universalis 1 (1):93-124.
    . Artificial Intelligence (AI) has long dealt with the issue of finding a suitable formalization for commonsense reasoning. Defeasible argumentation has proven to be a successful approach in many respects, proving to be a confluence point for many alternative logical frameworks. Different formalisms have been developed, most of them sharing the common notions of argument and warrant. In defeasible argumentation, an argument is a tentative (defeasible) proof for reaching a conclusion. An argument is warranted when it ultimately prevails over other (...)
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