Defeasible logic programming: an argumentative approach

Abstract

The work reported here introduces Defeasible Logic Programming (DeLP), a formalism that combines results of Logic Programming and Defeasible Argumentation. DeLP provides the possibility of representing information in the form of weak rules in a declarative manner, and a defeasible argumentation inference mechanism for warranting the entailed conclusions.In DeLP an argumentation formalism will be used for deciding between contradictory goals. Queries will be supported by arguments that could be defeated by other arguments. A query q will succeed when there is an argument A for q that is warranted, i. e. the argument A that supports q is found undefeated by a warrant procedure that implements a dialectical analysis.The defeasible argumentation basis of DeLP allows to build applications that deal with incomplete and contradictory information in dynamic domains. Thus, the resulting approach is suitable for representing agent's knowledge and for providing an argumentation based reasoning mechanism to agents.

Graph-Based Dispute Derivations in Assumption-Based Argumentation

“…Our notion of rule-minimality is related to the definition of argument structure (Def. 3.1) in [10].…”

“…[9][10][11][12]). This introduces both conceptual redundancy and inefficiency in standard methods of implementation, in that within an argument different rules for deriving the same conclusion may be used, potentially introducing unnecessarily points of attack and requiring additional defence efforts.…”

An Implemented Dialogue System for Inquiry and Persuasion

“…To do this, agents in our system may have epistemic knowledge (beliefs), represented by Garcia and Simari's Defeasible Logic Programming [6], as well as normative knowledge about the effects of actions.…”

“…The definition of a defeasible derivation is adapted from [6] to work with our assumption that all beliefs are defeasible. Definition 2: Let Ψ be a set of beliefs and α a literal.…”

Negotiation Among DDeLP Agents

“…To represent those deliberation processes we choose an alternative form of declarative programming, Defeasible Logic Programming (DeLP) [SCG94,Gar00,GS04]. This formalism combines Logic Programming with Defeasible Argumentation [Pol87,SL92,Pol95,Dun95,CML00,PV00], allowing the representation of tentative knowledge and leaving for the inference mechanism the task of finding the conclusions that the knowledge base warrants [CDSS03].…”