Handling incomplete information in the framework of THESEUS multicriteria sorting method

In this paper we face the multicriteria sorting problem considering that we have incomplete information. Multicriteria sorting is a particular case of classification problems. It consists in the assignment of some actions to some pre-defined classes. Classification refers to problems where the classes (groups, categories) have been defined in a nominal way. We use the term " incomplete information" to indicate the absence of a value in some criterion of the object to be assigned to a class (category).