Laurence Cholvy

Fusion: General concepts and characteristics

The problem of combining pieces of information issued from several sources can be encountered in various fields of application. This paper aims at presenting the different aspects of information fusion in different domains, such as databases, regulations, preferences, sensor fusion, etc., at a quite general level. We first present different types of information encountered in fusion problems, and different aims of the fusion process. Then we focus on representation issues which are relevant when discussing fusion problems. An important issue is then addressed, the handling of conflicting information. We briefly review different domains where fusion is involved, and describe how the fusion problems are stated in each domain. Since the term fusion can have different, more or less broad, meanings, we specify later some terminology with respect to related problems, that might be included in a broad meaning of fusion. Finally we briefly discuss the difficult aspects of validation and evaluation. © 2001 John Wiley & Sons, Inc.

Analyzing consistency of security policies

We discuss the development of a methodology for reasoning about properties of security policies. We view a security policy as a special case of regulation which specifies what actions some agents are permitted, obliged or forbidden to perform and we formalize a policy by a set of deontic formulae. We first address the problem of checking policy consistency and describe a method for solving it. The second point we are interested in is how to query a policy to know the actual norms which apply to a given situation. In order to provide the user with consistent answers, the normative conflicts which may appear in the policy must be solved. For doing so, we suggest using the notion of roles and define priorities between roles.

Towards a logical formalization of responsibility

In this paper, we are interested in formally modeling the concept of responsibility. It appears that this concept is essential in order to reason in many norm-governed organizations. However, obtaining a formal representation of responsibility is quite complex because of the very different meanings this concept can take. Therefore, our first task will be to clarify and classify the various meanings. We then propose a logical framework and show how it enables us to model several aspects of responsibility, This framework combines a deontic logic with a logic of actions and it distinguishes between direct and indirect agencies. We finally present an example to illustrate how this framework enables us to analyze some subtleties of a specific situation.

A Logical Approach to Multi-Sources Reasoning

This paper presents two logics for reasoning with information from several sources. The main problem is that the information might be contradictory; we show that ordering the different sources according to their reliability is a good way for solving this problem. The two logics which are presented, correspond to two attitudes one can take with respect to such an order.

Information Fusion in Logic: A Brief Overview

Information fusion is the process of deriving a single consistent knowledgebase from multiple knowledgebases. This process is important in many cognitive tasks such as decision-making, planning, design, and specification, that can involve collecting information from a number of potentially conflicting perspectives or sources, or participants. In this brief overview, we focus on the problem of inconsistencies arising in information fusion. In the following, we consider reasoning with inconsistencies, acting on inconsistencies, and resolving inconsistencies.

Checking regulation consistency by using SOL-resolution

This paper addresses the problem of regulation consistency checking. Regulations are sets of rules which express what is obligatory, permitted, forbidden and under which conditions. We first define a first order language to model regulations. Then we introduce a definition of regulation consistency. We show that checking the consistency of a regulation comes to generate some particular consequences of some first order formulas. Then, we show that we can apply Inoues inference rule, SOL-resolution, which is complete for generating, from some clauses, their consequences which satisfy a given condition.

Reasoning About Merged Information

More and more, computer science applications need to use information which is not provided by a single source of information but by several.

Automated Reasoning with Merged Contradictory Information Whose Reliability Depends on Topics

This paper presents a theorem prover for reasoning with information which is provided by several information sources and which may be contradictory.

Merging databases: Problems and examples

This paper focuses on databases merging, which is one particular case of data fusion. Databases merging is the process which consists of integrating, physically or virtually, the data provided by several databases. With examples throughout the paper, we stress the main problems raised by databases merging and we present, not exhaustively, some solutions. The topics receiving deepest study are: cases matching, inconsistency handling and summarizing data. © 2001 John Wiley & Sons, Inc.

Solving normative conflicts by merging roles

This paper addresses the problem of conflicting norms. The solution we describe is based on the concept of role: a role defines some permissions, obligations and prohibitions which are supposed free of conflicts. As soon as an individual plays a role, he inherits the set of norms associated with this role. We show that conflicting norms arise because an individual may play different roles. The central idea of our paper is to consider that it is possible to make a judgement of priority between the roles an individual plays, in order to decide which are the actual norms which apply in a given situation. This priority may be chosen by the individual or may be dependent on the structure which may exist between roles. Our paper mainly describes the axiomatic part of a logic for reasoning about norms associated with primitive roles as well as with composite roles obtained by merging several roles.