Title:
On the semantic of partial meet multiple contraction

Author:
Eduardo Fermé
(Université de Madeire)

Abstract:
In logic of theory change, the standard model is AGM, proposed by
Alchourroon, Gaardenfors and Makinson [AGM85]. This paper focuses
on the extension of AGM that accounts for contractions of a theory by
a set of sentences instead of only by a single sentence. Fuhrmann and
Hansson [Han89, FH94] generalized Partial Meet Contraction to the
case of contractions by (possibly non-singleton) sets of sentences. In
this talk we present the possible worlds semantics for partial meet
multiple contractions.

We search for an appropriate way of denying, and the problems to construct
partial meet multiple contractions in a Grove's spheres system, and then we 
propose a new class of multiple contraction operations based on Grove’s
spheres system. Furthermore, we show that this new class of functions is a
subclass of the class of the partial meet multiple contractions.