Automated identification of protein-ligand interaction features using Inductive Logic Programming: a hexose binding case study

Table 5 Background knowledge predicates for the two binding site representations

Representation	Background knowledge predicates
atom-only	center_coords/2, has_atom/4, dist/4
amino acid	has_aminoacid/3, atom_to_center_dist/4,
	atom_to_atom_dist/6, diff_aminoacid/2

The /N indicates the arity of the background knowledge predicate. For instance, given a binding site, the center_coords predicate returns the coordinates of its center (1 input + 1 output arguments = 2).