C(12,5,2) = 9

Method of Construction: random greedy covering

Lower Bound: Horsley, Theorem 14a, r=3, d=1

  1  3  4  6 12
  5  8  9 10 11
  2  3  5  7  8
  2  6 10 11 12
  1  2  4  7  9
  1  5  6  8 12
  1  3  7 10 11
  3  6  7  9 12
  4  5  8 10 11