In comparison to possibility theory, the Transferable Belief Model (TBM) - a nonprobabilistic interpretation of Dempster-Shafer theory - enjoys little choice in terms of aggregation operators for the fusion of information. In this thesis, the problem of introducing some flexibility for the combination of belief functions - the mathematical tool allowing the representation of information in the TBM - is tackled. Our first contribution is to introduce infinite families of conjunctive and disjunctive combination rules for belief functions, mimicking thus the situation in possibility theory for what concerns conjunctive and disjunctive operators. Our second contribution is a set of results making an infinite family of combination rules, introduced initially in a pure formal manner and called the alpha-junctions, of practical interest. First, we show that these rules correspond to a particular form of knowledge about the truthfulness of the sources of information. Second, we provide several new simple means for the computation of the combination by an alpha-junction.
