Belief Revision by Sets of Sentences

The aim of this paper is to extend the system of belief revision developed by Alchourron, Gardenfors and Makinson (AGM) to a more general framework.This extension enables a treatment of revision not only by single sentences but also by any sets of sentences, especially by infinite sets. The extended revision and contraction operators will be called general ones, respectively. A group of postulates for each operator is provided in such a way that it coincides with AGM's in the limit case. A notion of the nice-ordering partition is introduced to characterize the general contraction operation. A comp ut ation- orient ed ap-proach is provided for belief revision operations.

Agent Belief with Credibility and Its Revision Mechanism

An approach to characterize the credibility of beliefs of an agent is proposed in this paper, which can define the uncertainty of beliefs, calculation rules and inference rules about credibility and a method for belief revision based on abductive reasoning is also given. When an agent receives some new information, if the new information is consistent with the current belief set, then incorporate this new information with an appropriate credibility, otherwise the choice will be different depending on the characters of agents, and the deliberated agents will choose the belief with a better explanation under the current belief set. Removing one belief may cause the removal of those beliefs that, together with others, logically entail the formula to be removed. A method based on abduction is proposed to solve these problems.

Default Reasoning and Belief Revision:A Syntax-Independent Approach

As an important variant of Relier's default logic, Poole (1988) developed a nonmonotonic reasoning framework in the classical first-order language. Brewka and Nebel extended Poole's approach in order to enable a representation of priorities between defaults. In this paper a general framework for default reasoning is presented, which can be viewed as a generalization of the three approaches above. It is proved that the syntax-independent default reasoning in this framework is identical to the general belief revision operation introduced by Zhang et al. (1997). This result provides a solution to the problem whether there is a correspondence between belief revision and default logic for the infinite case. As a by-product, an answer to the question, raised by Mankinson and Gardenfors (1991), is also given about whether there is a counterpart contraction in nonmonotonic logic.

Operational and Complete Approaches to Belief Revision

Two operational approaches to belief revision are presented in this paper. The rules of Rcalculus are modified in order to deduce all the maximal consistent subsets. Another set of rules is given in order to deduce all the minimal inconsistent subsets. Then a procedure, which can generate all the maximal consistent subsets, is presented. They are complete approaches, since all the maximal consistent subsets can be deduced or generated. In this paper, only the case of propositional logic is considered.

Negotiation Model for Shopping Agents in E-marketplace

Automated negotiation is the key techniques for reaching agreements in agent-mediated electronic commerce. Current automated negotiation models assume that users know the value of the product or service they want to buy and provide their agents with a reservation price, and the agents make offers and reach agreements with other agents according to this reservation price. However, in real world electronic marketplaces users probably do not know the exact value of the item, which is in terms of price, and the reservation price they set to their agents only means the maximum price they are willing to pay for the item. In this paper, we propose a negotiation model to deal with the valuation problem. The shopping agent in our model can deliberate the market price and the seller agent’s reservation price from public available information and the seller agent’s proposals. Also in order to conform with the real world negotiation conditions, we introduce negotiation features of real world human shopping such as multiple sellers, valuation, ultimatum, and learning from available information, etc. into our model.

Managing Software Requirements Changes Based on Negotiation-Style Revision

For any proposed software project,when the software requirements specification has been established,requirements changes may result in not only a modification of the requirements specification but also a series of modifications of all existing artifacts during the development.Then it is necessary to provide effective and flexible requirements changes management.In this paper,we present an approach to managing requirements changes based on Booth＇s negotiation-style framework for belief revision.Informally,we consider the current requirements specification as a belief set about the systemto-be.The request of requirements change is viewed as new information about the same system-to-be.Then the process of executing the requirements change is a process of revising beliefs about the system-to-be.We design a family of belief negotiation models appropriate for different processes of requirements revision,including the setting of the request of requirements change being fully accepted,the setting of the current requirements specification being fully preserved,and that of the current specification and the request of requirements change reaching a compromise.In particular,the prioritization of requirements plays an important role in reaching an agreement in each belief negotiation model designed in this paper.

A sound and complete R-calculi with respect to contraction and minimal change

AGM postulates are for belief revision （revision by a single belief）, and DP postulates are for iterated revision （revision by a finite sequence of beliefs）. R-calculus is given for R-configurations △｜Г, where △ is a set of atomic formulas or the negations of atomic formulas, and Г is a finite set of formulas. We shall give two R-calculi C and M （sets of de- duction rules） such that for any finite consistent sets Г, △of formulas in the propositional logic, there is a consistent set ⊙ Г C of formulas such that △IГ → △, ⊙ is provable and⊙ is a contraction of F by A or a minimal change of F by A; and prove that C and M are sound and complete with respect to the contraction and the minimal change, respectively.