2. The method claimed in claim 1 , wherein the new probability set is a subset of the predefined probability set.
2. The method claimed in claim 1 , wherein the new probability set is a subset of the predefined probability set. 3. The method claimed in claim 2 , wherein assigning each of the symbols includes defining the mapping by determining, for each probability of the predefined probability set, to which one of the probabilities from the new probability set it is mapped.