The concept of a constraint graph. (a) A tree constraint (ni, nj, bt) of the path that connects ni and nj in a pedigree graph G will be transformed into an edge between ni and nj with weight bt in the corresponding constraint graph G*. (b) A constraint graph. There are three edges (n3, n11), (n7, n5), and (n9, n5) in the constraint graph, which means that there are three tree constraints in the linear system. Note that the constraint graph is disconnected and contains several connected components.
Lai et al. BMC Bioinformatics 2012 13(Suppl 17):S19 doi:10.1186/1471-2105-13-S17-S19