Abstract: Methods can include receiving a graphbase comprising a first plurality of nodes and a plurality of edges representing covering-covered relationships between the nodes. Each node can comprise a plurality of node parameters such as a NodeNumber, a Reachable Interval, and an OwnTree Interval. For a traversal ordering of nodes, nodes comprised within the OwnTree Interval are reachable from the node, nodes comprised within the Reachable Interval may be reachable from the node, and nodes comprised within neither interval are not reachable by the node. Methods can additionally include the steps of receiving a first and second sub-set of nodes, the sub-sets being a sub-set of the first plurality of nodes. Furthermore, a relationship between the first and second sub-set can be determined using the NodeNumber, the OwnTree Interval, and the Reachable Interval.