Reis, Maurício D. L.Fermé, EduardoPeppas, Pavlos2021-05-272021-05-272016Reis, M. D., Fermé, E., & Peppas, P. (2016). Construction of system of spheres-based transitively relational partial meet multiple contractions: An impossibility result. Artificial Intelligence, 233, 122-141.http://hdl.handle.net/10400.13/3444In this paper we show that, contrary to what is the case in what concerns contractions by a single sentence, there is not a system of spheres-based construction of multiple contractions which generates each and every transitively relational partial meet multiple contraction. Before proving the general result, we consider the class of system of spheres-based mul tiple contractions introduced in [17,5] and show that this class neither subsumes nor is subsumed by the class of transitively relational partial meet multiple contractions. Furthermore, we propose two system of spheres-based constructions of multiple con tractions which generate (only) transitively relational partial meet multiple contractions. Therefore we can conclude that, although it is impossible to obtain a system of spheres based definition of all the transitively relational partial meet multiple contractions, there are classes of system of spheres-based multiple contractions which are subsumed by the class of transitively relational partial meet multiple contractions.engBelief changeTheory contractionMultiple contractionSystem of spheresTransitively relational.Faculdade de Ciências Exatas e da Engenhariajournal article10.1016/j.artint.2016.01.001