Within a specific application there are always some global data members as the output and error streams, zero tolerances, a big number representing ``infinity'', and some functions related with these data. For the same reasons we discussed already in the description of the class ABA_ABACUSROOT we should avoid storing these data in global variables. It is also not reasonable to add these data to the class ABA_ABACUSROOT, because it would blow up every derived class of ABA_ABACUSROOT and it is neither necessary nor desired to have extra output streams, zero tolerances, etc., for every object.
Instead of implementing this data directly in the class ABA_MASTER we designed an extra class ABA_GLOBAL , from which the class ABA_MASTER is derived. The reason is that there are several classes, especially some basic data structures, which might be useful in programs that are not branch-and-bound algorithms. To simplify their reuse these classes have a pointer to an object of the class ABA_GLOBAL instead of one to an object of the class ABA_MASTER.