B. ROY's paper discusses a method called ELECTRE for classification and choice in the presence of multiple perspectives. The method involves defining a set of objects and multiple criteria (points of view) that can be used to establish complete pre-orders. The goal is to determine which subset of objects can be eliminated to narrow the choice problem or to reveal a dichotomous ranking. Two indicators, concordance and discordance, are used to define a relationship that allows for the partitioning of objects based on the concept of a graph's nucleus. Examples are provided to illustrate the approach. The paper also outlines some generalizations that can be used to address more complex problems. The method is applied to various scenarios, including the selection of new activities for a company and the evaluation of candidates for a competition. The paper introduces the concepts of concordance and discordance, which are used to determine whether one object dominates another based on the criteria. The method is then used to define a dominance relationship, which is represented as a graph. The paper also discusses the concept of a nucleus, which is a subset of objects that are stable and non-dominated by others. The method is applied to various examples, including the selection of new products and the evaluation of candidates. The paper concludes with some possible extensions of the method, including the use of different criteria and the application of the method to more complex problems.B. ROY's paper discusses a method called ELECTRE for classification and choice in the presence of multiple perspectives. The method involves defining a set of objects and multiple criteria (points of view) that can be used to establish complete pre-orders. The goal is to determine which subset of objects can be eliminated to narrow the choice problem or to reveal a dichotomous ranking. Two indicators, concordance and discordance, are used to define a relationship that allows for the partitioning of objects based on the concept of a graph's nucleus. Examples are provided to illustrate the approach. The paper also outlines some generalizations that can be used to address more complex problems. The method is applied to various scenarios, including the selection of new activities for a company and the evaluation of candidates for a competition. The paper introduces the concepts of concordance and discordance, which are used to determine whether one object dominates another based on the criteria. The method is then used to define a dominance relationship, which is represented as a graph. The paper also discusses the concept of a nucleus, which is a subset of objects that are stable and non-dominated by others. The method is applied to various examples, including the selection of new products and the evaluation of candidates. The paper concludes with some possible extensions of the method, including the use of different criteria and the application of the method to more complex problems.