Relation R (non transitive): R(a,a), R(a,d) R(b,b), R(b,c) R(c,c) R(d,b), R(d,d) R(0,x) x = 0, a, b, c, d, 1 R(x,1) x = 0, a, b, c, d, 1 Orthosupplement: 0 a b c d 1 1 c d a b 0 Candidates to fill: (0, a), (0, b), (0, c), (0, d), (0, 1)*, (a, b), (a, c)*, (b, d)*, (d, d)