Propagation of linguistic labels in causal networks

The problem of the propagation of linguistic labels in polytrees is considered. The approach is purely symbolic and does not consider semantic translations of the terms. It starts from a general axiomatic framework to propagate information in graphs, which is later particularized to the case of linguistic labels. It is observed that it is very difficult to define operations with linguistic labels verifying all the required properties, mainly because of the lack of granularity of finite sets of terms. To cope with these problems, modifications of the propagation algorithms are proposed