The heuristics we describe in this section compute Core in time linear with the number of attributes in . These heuristics reference the set of containers and the three functions and , but they do not reference the full set of attributes. In addition, these heuristics do not enumerate , but they do reference the configuration of hosts (to reference the configuration of a host , they reference and ). Thus, the container/sub-container hierarchy is the only data structure that the heuristics use to compute cores.