predicate Neighbor(position,position) [position1,position2] Neighbor(position1,position2) <-> ((position1=1 & position2=2) | (position1=1 & position2=3) | (position1=1 & position2=4) | (position1=2 & position2=3) | (position1=2 & position2=4) | (position1=3 & position2=4) | (position1=5 & position2=6) | (position1=5 & position2=7) | (position1=5 & position2=8) | (position1=6 & position2=7) | (position1=6 & position2=8) | (position1=7 & position2=8) | (position2=1 & position1=2) | (position2=1 & position1=3) | (position2=1 & position1=4) | (position2=2 & position1=3) | (position2=2 & position1=4) | (position2=3 & position1=4) | (position2=5 & position1=6) | (position2=5 & position1=7) | (position2=5 & position1=8) | (position2=6 & position1=7) | (position2=6 & position1=8) | (position2=7 & position1=8) | (position1=4 & position2=7) | (position2=4 & position1=7)). ; Prolog code starts with ;:- ;:- include(sanity_equals_01_extra).