An associative container is exactly that how it is defined in
STL:
an unambigous mapping of one set of values in another. We did not have any intention to reinvent the wheel,
so there is only a couple of specialized associative containers in the Polymake Template Library.
In the most cases the standard std::map and std_ext::hash_map
do their job well.
Map
std::map if you have a complex key type and want to make profit from an accelerated
key comparator class.
FaceMap