Fig. 3

The principles of orthologs search in Task I. A Forward check of a homolog X′ in species A of a given gene X in species R that involves, e.g., two witnesses: Y and Z in R and Y′ and Z′ in A. The dashed arrow represents the α-homology condition, and the solid arrow represents the β-homology (see for the explanation of α- and β-homology Step 2 in section A of Methods). The brackets indicate the chosen neighborhoods of the genes X and X′, in which the witnesses are sought. The witnesses may be arbitrarily positioned and directed within the neighborhood. B Backward check for the existence of an alternative U that is more similar to candidate X′ than X that involves, e.g., two witnesses. The dashed arrow represents the α-homology condition, and the solid arrow represents the β-homology. The brackets indicate the chosen neighborhoods of the genes X and X′, in which the witnesses are sought. The witnesses may be arbitrarily positioned and directed within the neighborhood