  In this article we present two ways of structuring bodies of evidence, which
allow us to reduce the complexity of the operations usually performed in the
framework of evidence theory. The first structure just partitions the focal
elements in a body of evidence by their cardinality. With this structure we are
able to reduce the complexity on the calculation of the belief functions Bel,
Pl, and Q. The other structure proposed here, the Hierarchical Trees, permits
us to reduce the complexity of the calculation of Bel, Pl, and Q, as well as of
the Dempster's rule of combination in relation to the brute-force algorithm.
Both these structures do not require the generation of all the subsets of the
reference domain.
