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