Papers by Odinaldo Rodrigues
Argumentation Semantics for Prioritised Default Logic
ABSTRACT
A Numerical Approach to the Merging of Argumentation Networks
Lecture Notes in Computer Science, 2012
ABSTRACT In this paper, we propose a numerical approach to the problem of merging of argumentatio... more ABSTRACT In this paper, we propose a numerical approach to the problem of merging of argumentation networks. The idea is to consider an augmented network containing the arguments and attacks of all networks to be merged and then associate a weight to each of its components based on how they are perceived by the agents associated with the local networks. The combined weighted network is then used to define a system of equations from which the overall strength of the arguments is calculated.
Logica Universalis
Given an argumentation network with initial values to the arguments, we look for algorithms which... more Given an argumentation network with initial values to the arguments, we look for algorithms which can yield extensions compatible with such initial values. We find that the best way of tackling this problem is to offer an iteration formula that takes the initial values and the attack relation and iterates a sequence of intermediate values that eventually converges leading to an extension. The properties surrounding the application of the iteration formula and its connection with other numerical and non-numerical techniques proposed by others are thoroughly investigated in this paper.
BDI reasoning with normative considerations
Engineering Applications of Artificial Intelligence, 2015
ABSTRACT Systems of autonomous and self-interested agents interacting to achieve individual and c... more ABSTRACT Systems of autonomous and self-interested agents interacting to achieve individual and collective goals may exhibit undesirable or unexpected behaviour if left unconstrained. Norms have been widely proposed as a means of defining and enforcing societal constraints by using the deontic concepts of obligations, permissions and prohibitions to describe what must, may and should not be done, respectively. However, recent efforts to provide norm-enabled agent architectures that guide plan choices suffer from interfering with an agent׳s reasoning process, and thus limit the agent׳s autonomy more than is required by the norms alone. In this paper we describe an extension of the Beliefs–Desires–Intentions (BDI) architecture that enables normative reasoning used to help agents choose and customise plans taking norms into account. The paper makes three significant contributions: we provide a formal framework to represent norms compactly and to manage them; we present a formal characterisation of the normative positions induced by norms of an agent׳s execution within a given time period; and finally, we put forth a mechanism for plan selection and ranking taking into consideration a set of normative restrictions.
We are happy to present our new book to the community. Although this is a book on revision theory... more We are happy to present our new book to the community. Although this is a book on revision theory, it uses general methodologies which are applied in other areas of logic. We would like to highlight these methodologies in this preface.
Journal of Logic, Language and Information, 1997
Abstract. We point out a simple but hitherto ignored link between the theory of updates, the theo... more Abstract. We point out a simple but hitherto ignored link between the theory of updates, the theory of counterfactuals, and classical modal logic: update is a classical existential modality, counterfactual is a classical universal modality, and the accessibility relations corresponding to these ...
PROMAL - Programming in Modal Action Logic
Without Abstract
Iterated Revision and Automatic Similarity Generation
ABSTRACT From the introduction: In the original AGM formulation, revision is a function ∘ that ta... more ABSTRACT From the introduction: In the original AGM formulation, revision is a function ∘ that takes a belief set K and a sentence A as inputs and returns as a result a revised belief set K∘A. Because the two arguments of ∘ are of different types – the infinite set K and the finite formula A – in this particular setting they cannot be interchanged. However, it is well-known that H. Katsuno and A. O. Mendelzon [“On the difference between updating a knowledge base and revising it”, in: Belief revision. Cambridge: Univ. Press. 183–203 (1992; Zbl 0801.68151)] provided a characterization of the AGM postulates for belief sets that are finitely representable as a formula K. In this scenario, K, A and K∘A are all formulae and therefore can be applied in the revision function in any of its arguments.
Journal of Logic and Computation, 2003
This paper presents a framework in which priorities in a belief base can be specified and used in... more This paper presents a framework in which priorities in a belief base can be specified and used in the resolution of conflicts. Priorities are given in terms of a partial pre-order associated with the sentences in the base. When the new information is given the highest priority, it is accepted, thus complying with the success postulate of the AGM theory of belief revision. However, in general, priorities can be specified in a very flexible way and an input sentence placed anywhere in the previous ordering. The result or conclusion of a belief base can be computed into a sentence, allowing the method to be used in the reasoning of more complex structures where nodes in the structure are themselves prioritized bases. Embedded groups of prioritized bases are recursively resolved before the embedding structure is. The method combines reasoning about inconsistency and priorities in an elegant way.
Research on Language and Computation
Research on Language and Computation, 2003
We are pleased to present the first issue of the journal of Research on Language and Computation.... more We are pleased to present the first issue of the journal of Research on Language and Computation. The journal responds to the need for a forum in which researchers working at the interface of logic, formal grammar, and ...
Structured Revision: Non-linear Methods for Information Change
In the previous chapter we proposed a framework in which belief bases were represented as a struc... more In the previous chapter we proposed a framework in which belief bases were represented as a structured set of components. These components were related according to a linear ordering expressing the relative priorities of each one of them. Linear PDBs and SDBs are conceptually simpler because they allow a direct application of the operators defined in earlier chapters. Each non-terminal component of the base can just be recursively reduced by means of the operators into a sentence representing the belief state of the agent.
Revision by Translation (short version
ABSTRACT In this paper, we show that it is possible to accomplish belief revision in any logic wh... more ABSTRACT In this paper, we show that it is possible to accomplish belief revision in any logic which is translatable to classical logic. We give the example of the propositional modal logic K and show that a belief operation in K dened in terms of K 0 s translation to classical logic veries the AGM postulates.
In this paper, we consider a number of different ways of reasoning about voting as a problem of c... more In this paper, we consider a number of different ways of reasoning about voting as a problem of conciliating contradictory interests. The mechanisms that do the reconciliation are belief revision and belief merging. By investigating the relationship between different voting strategies and their associated counterparts in revision theory, we find that whereas the counting mechanism of the voting process is more easily done at the meta-level in belief merging, it can be brought to the object level in base revision. In the former case, the counting can be tweaked according to the aggregation procedure used, whereas in base revision, we can only rely on the notion of minimal change and hence the syntactical representation of the voters' preferences plays a crucial part in the process. This highlights the similarities between the revision approaches on the one hand and voting on the other, but also opens up a number of interesting questions.
Journal of Logic and Computation, 2009
In belief revision, an agent is faced with the problem of choosing between several alternatives w... more In belief revision, an agent is faced with the problem of choosing between several alternatives when trying to restore consistency to theory. Ideally, the choice process is conducted in a way that verifies a number of fairness principles. On the other hand, belief merging concerns with the problem of determining a group's beliefs from individual members' beliefs that are not always compatible with each other. Similarly, in voting systems, a social welfare function takes individual preferences into account in order to produce a collective preference. Here again certain fairness principles are desirable. In this paper, we investigate the relationship between revision, merging and voting.
Belief Revision
The investigation of how humans reach conclusions from given premises has long been the subject o... more The investigation of how humans reach conclusions from given premises has long been the subject of intense research in the literature. It was the basis of the development of classical logic, for instance. The investigation of how humans change their minds in the face of new contradictory information is however somewhat more recent. Early accounts include the work of Ramsey [Ramsey, 1931; Ramsey, 1990] in his insights into conditional statements, for instance, and subsequently the work on conditionals by Stalnaker [Stalnaker,1968b] and by Lewis [Lewis, 1973], among others. More recent work on the formalisation of common-sense reasoning, sometimes also called non-monotonic reasoning, include [McCarthy, 1958; Brewka, 1990; Łukaszewicz, 1990; Reiter, 1980].
Object-Level Deletion
We have seen that the interesting cases for belief revision involve the removal of information fr... more We have seen that the interesting cases for belief revision involve the removal of information from the existing belief set. Therefore, the investigation of techniques for deletion plays an important role in the process.
Iterating Revision
In the previous chapter we presented some operators that could be used to perform revision in the... more In the previous chapter we presented some operators that could be used to perform revision in the AGM sense and action updates complying with Katsuno and Mendelzon’s semantical characterisation of these operations. It is well known that even though the postulates capture the intuitions behind rational changes of belief and the expected properties of the execution of actions, they are severely limited by the lack of extra information supporting the representation of the current state of affairs or beliefs. Some of these limitations were discussed in Chapter 2 in the sections related to the iteration of the revision process. In particular, the realisation of the initial corpus of beliefs (or the description of the world in the case of action updates) into a unit with little structure (a formula in the finite case or a theory, otherwise) brings several difficulties to reasoning about more sophisticated scenarios.
Algorithmic Context Revision
In Chapter 3, we provided a number of operations for belief change. The revision operator was the... more In Chapter 3, we provided a number of operations for belief change. The revision operator was then used to analyse the process of iteration in Chapter 4, making use of the fact that consecutive inputs to a database (belief base) naturally give rise to a linear order on the beliefs in that database. We dropped the linearity restriction in Chapter 5 and considered alternatives for dealing with the extra structure available in the database. However, in all of the above, we have not looked into (or attempted to modify) the particular characteristics of the logic L used for the reasoning, apart from the obvious considerations on consistency of the database itself.
Conclusions and Discussions
In this book we provided a comprehensive set of methodologies to tackle the problem of belief rev... more In this book we provided a comprehensive set of methodologies to tackle the problem of belief revision. The methodologies determine acceptability criteria for the result of the revision operation based on the context in which the operation takes place. In what follows, we summarise the main points raised in the book and we end with some discussions in Section 9.2.
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Papers by Odinaldo Rodrigues