Fermé, EduardoReis, Maurício D. L.2021-05-282021-05-282011Fermé, E., & Reis, M. D. (2012). System of spheres-based multiple contractions. Journal of Philosophical Logic, 41(1), 29-52.http://hdl.handle.net/10400.13/3448We propose a new class of multiple contraction operations — the system of spheres-based multiple contractions — which are a generalization of Grove’s system of spheres-based (singleton) contractions to the case of contractions by (possibly non-singleton) sets of sentences. Furthermore, we show that this new class of functions is a subclass of the class of the partial meet multiple contractions.engBelief changeTheory contractionMultiple contractionPossible worlds semanticsSystem of spheres.Faculdade de Ciências Exatas e da Engenhariajournal article10.1007/s10992-011-9197-z