Figure 8.

The plan tree generated from the conjunctive query. The plan tree is a binary tree where nodes are represented by variables of the predicate arguments in the conjunctive query and the edges are predicates containing the two variables of the nodes they are linking.

Briache et al. BMC Bioinformatics 2012 13(Suppl 1):S7   doi:10.1186/1471-2105-13-S1-S7