Dialectical Frameworks (ADFs) are argumentation frameworks where each node is associated with an ... more Dialectical Frameworks (ADFs) are argumentation frameworks where each node is associated with an acceptance condition. This allows us to model different types of dependencies as supports and attacks. Previous studies provided a translation from Normal Logic Programs (NLPs) to ADFs and proved the stable models semantics for a normal logic program has an equivalent semantics to that of the corresponding ADF. However, these studies failed in identifying a semantics for ADFs equivalent to a three-valued semantics (as partial stable models and well-founded models) for NLPs. In this work, we focus on a fragment of ADFs, called Attacking Dialectical Frameworks (ADF+s), and provide a translation from NLPs to ADF+s robust enough to guarantee the equivalence between partial stable models, well-founded models, regular models, stable models semantics for NLPs and respectively complete models, grounded models, preferred models, stable models for ADFs. In addition, we define a new semantics for A...
Proceedings of the 33rd Annual ACM Symposium on Applied Computing, 2018
This paper introduces a purely model-theoretic characterisation of a labelling-based semantics fo... more This paper introduces a purely model-theoretic characterisation of a labelling-based semantics for argumentation frameworks. The meaning of such framework is determined declaratively by their unique minimum model (which is guaranteed to exist) or equivalently by a kind of immediate consequences operator. The distinctive aspect of our semantics is that it is settled on an infinite-valued approach. Indeed, we prove that it reduces to the grounded semantics when collapsed to a three-valued scenario.
Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing, 2019
This work investigates an alternative characterization of semantics for Assumption-Based Argument... more This work investigates an alternative characterization of semantics for Assumption-Based Argumentation (ABA) frameworks. The semantics of ABA frameworks are traditionally retrieved by the corresponding concepts of assumption extensions and assumption labellings, which only evaluate a subset of literals in the framework's language which are called assumptions. We argue about the interplay of non-assumptions in ABA frameworks and take inspiration from similarities between ABA and Logic Programming (LP) to propose new operations and semantic computation concerning ABA frameworks. To do so, we followed Przymusinski's work on Three-Valued Stable Models for LP to define interpretations and models for ABA frameworks (which also evaluate non-assumptions) and investigate whether this approach provides different results from the original. Amongst other results, we show that our complete model semantics is equivalent to the complete assumption labelling semantics for flat ABA frameworks, but the semi-stable model semantics is not equivalent to the semi-stable assumption labelling semantics.
Page 1. Abduction-Based Search for Cooperative Answers Samy S?? and Jo??ao Alc??ntara Universidad... more Page 1. Abduction-Based Search for Cooperative Answers Samy S?? and Jo??ao Alc??ntara Universidade Federal do Cear?? samy@lia.ufc.br, jnando@lia.ufc.br Abstract. We propose that agents may use abductive reasoning to adopt a Cooperative Answering behavior. ...
Dialectical Frameworks (ADFs) are argumentation frameworks where each node is associated with an ... more Dialectical Frameworks (ADFs) are argumentation frameworks where each node is associated with an acceptance condition. This allows us to model different types of dependencies as supports and attacks. Previous studies provided a translation from Normal Logic Programs (NLPs) to ADFs and proved the stable models semantics for a normal logic program has an equivalent semantics to that of the corresponding ADF. However, these studies failed in identifying a semantics for ADFs equivalent to a three-valued semantics (as partial stable models and well-founded models) for NLPs. In this work, we focus on a fragment of ADFs, called Attacking Dialectical Frameworks (ADF+s), and provide a translation from NLPs to ADF+s robust enough to guarantee the equivalence between partial stable models, well-founded models, regular models, stable models semantics for NLPs and respectively complete models, grounded models, preferred models, stable models for ADFs. In addition, we define a new semantics for A...
Proceedings of the 33rd Annual ACM Symposium on Applied Computing, 2018
This paper introduces a purely model-theoretic characterisation of a labelling-based semantics fo... more This paper introduces a purely model-theoretic characterisation of a labelling-based semantics for argumentation frameworks. The meaning of such framework is determined declaratively by their unique minimum model (which is guaranteed to exist) or equivalently by a kind of immediate consequences operator. The distinctive aspect of our semantics is that it is settled on an infinite-valued approach. Indeed, we prove that it reduces to the grounded semantics when collapsed to a three-valued scenario.
Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing, 2019
This work investigates an alternative characterization of semantics for Assumption-Based Argument... more This work investigates an alternative characterization of semantics for Assumption-Based Argumentation (ABA) frameworks. The semantics of ABA frameworks are traditionally retrieved by the corresponding concepts of assumption extensions and assumption labellings, which only evaluate a subset of literals in the framework's language which are called assumptions. We argue about the interplay of non-assumptions in ABA frameworks and take inspiration from similarities between ABA and Logic Programming (LP) to propose new operations and semantic computation concerning ABA frameworks. To do so, we followed Przymusinski's work on Three-Valued Stable Models for LP to define interpretations and models for ABA frameworks (which also evaluate non-assumptions) and investigate whether this approach provides different results from the original. Amongst other results, we show that our complete model semantics is equivalent to the complete assumption labelling semantics for flat ABA frameworks, but the semi-stable model semantics is not equivalent to the semi-stable assumption labelling semantics.
Page 1. Abduction-Based Search for Cooperative Answers Samy S?? and Jo??ao Alc??ntara Universidad... more Page 1. Abduction-Based Search for Cooperative Answers Samy S?? and Jo??ao Alc??ntara Universidade Federal do Cear?? samy@lia.ufc.br, jnando@lia.ufc.br Abstract. We propose that agents may use abductive reasoning to adopt a Cooperative Answering behavior. ...
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Papers by João Fernando Lima Alcântara