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Default Logic (default + logic)

Distribution by Scientific Domains
Information Science and Computing100%

Selected Abstracts

On Resolving Conflicts Between Arguments

COMPUTATIONAL INTELLIGENCE, Issue 3 2000
Nico Roos
Argument systems are based on the idea that one can construct arguments for propositions,structured reasons justifying the belief in a proposition. Using defeasible rules, arguments need not be valid in all circumstances, therefore, it might be possible to construct an argument for a proposition as well as its negation. When arguments support conflicting propositions, one of the arguments must be defeated, which raises the question of which (sub-) arguments can be subject to defeat. In legal argumentation, metarules determine the valid arguments by considering the last defeasible rule of each argument involved in a conflict. Since it is easier to evaluate arguments using their last rules, can a conflict be resolved by considering only the last defeasible rules of the arguments involved? We propose a new argument system where, instead of deriving a defeat relation between arguments, arguments for the defeat of defeasible rules are constructed. This system allows us to determine a set of valid (undefeated) arguments in linear time using an algorithm based on a JTMS, allows conflicts to be resolved using only the last rules of the arguments, allows us to establish a relation with Default Logic, and allows closure properties such as cumulativity to be proved. We propose an extension of the argument system based on a proposal for reasoning by cases in default logic. [source]

On the dynamics of default reasoning

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 12 2002
Grigoris Antoniou
Default logic is a prominent rigorous method for reasoning with incomplete information based on assumptions. It is a static reasoning approach, in the sense that it doesn't reason about changes and their consequences. On the other hand, its nonmonotonic behavior appears when changes to a default theory are made. This paper studies the dynamic behavior of default logic in the face of changes. We consider the operations of contraction and revision, present several solutions to these problems, and study their properties. © 2002 Wiley Periodicals, Inc. [source]

On Resolving Conflicts Between Arguments

COMPUTATIONAL INTELLIGENCE, Issue 3 2000
Nico Roos
Argument systems are based on the idea that one can construct arguments for propositions,structured reasons justifying the belief in a proposition. Using defeasible rules, arguments need not be valid in all circumstances, therefore, it might be possible to construct an argument for a proposition as well as its negation. When arguments support conflicting propositions, one of the arguments must be defeated, which raises the question of which (sub-) arguments can be subject to defeat. In legal argumentation, metarules determine the valid arguments by considering the last defeasible rule of each argument involved in a conflict. Since it is easier to evaluate arguments using their last rules, can a conflict be resolved by considering only the last defeasible rules of the arguments involved? We propose a new argument system where, instead of deriving a defeat relation between arguments, arguments for the defeat of defeasible rules are constructed. This system allows us to determine a set of valid (undefeated) arguments in linear time using an algorithm based on a JTMS, allows conflicts to be resolved using only the last rules of the arguments, allows us to establish a relation with Default Logic, and allows closure properties such as cumulativity to be proved. We propose an extension of the argument system based on a proposal for reasoning by cases in default logic. [source]

Defeasible logic with dynamic priorities

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2004
Grigoris Antoniou
Defeasible logic is a nonmonotonic reasoning approach based on rules and priorities. Its design supports efficient implementation, and it shows promise to be deployed successfully in applications. So far, only static priorities have been used, provided by an external superiority relation. In this article we show how dynamic priorities can be integrated, where priority information is obtained from the deductive process itself. Dynamic priorities have been studied for other related reasoning systems such as default logic and argumentation. We define a proof theory, study its formal properties, and provide an argumentation semantics. © 2004 Wiley Periodicals, Inc. [source]

On the dynamics of default reasoning

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 12 2002
Grigoris Antoniou
Default logic is a prominent rigorous method for reasoning with incomplete information based on assumptions. It is a static reasoning approach, in the sense that it doesn't reason about changes and their consequences. On the other hand, its nonmonotonic behavior appears when changes to a default theory are made. This paper studies the dynamic behavior of default logic in the face of changes. We consider the operations of contraction and revision, present several solutions to these problems, and study their properties. © 2002 Wiley Periodicals, Inc. [source]