“…In this paper, we consider a more general version of compositional models, namely, models generated by compositional expressions [27,28] and formed by distributions whose values (such as probabilities) can be added, multiplied and divided according to the algebraic rules of a semifield [27], which is defined in the Appendix (see Section 10). Owing to their generality, such models find applications also to multidimensional databases (SUM-data, MAX-data, MIN-data, Boolean data), in which query answering requires to combine data stored in distinct tables [26].…”