Fig. 2

Overview of indirect alignment. At first, the query and reference networks Q and R _i are aligned. Let the matching function be ψ _i . For instance, query node b is matched with the reference node f (i.e., ψ _i (b)=f). In the reference generation phase, we stored the non-overlapping, significant mappings of R _i in the target network T. Let ϕ _i1 be one of these stored mapping, and reference node f is matched with the target node g (i.e., ϕ _i1(f)=g). Therefore, the indirect mapping of query node b is target node g (i.e., ϕ _i1(ψ _i (b))=g)