 A new set of postulates for merging operators and the distinction (in terms of axioms they satisfy) between arbitration and majority operators were introduced by Konieczny and Pino Pérez (1998). In subsequent works (Konieczny and Pino Pérez 1999, 2002) they extended the framework to include merging under integrity constraints, that is, a set of exogenously imposed conditions that have to be satisfied by the merged base (Kowalski 1978; Reiter 1988). In the next section we present the formal framework introduced by Konieczny and Pino Pérez, which is now the standard framework for belief merging as it overcomes the limitations of the previous proposals.