lower bound = 7

C(13,6,2) = 7

Method of Construction: lex covering

Lower Bound: Schonheim

  1  2  3  4  5  6
  1  7  8  9 10 11
  2  3  7  8 12 13
  4  5  9 10 12 13
  2  3  6  9 10 11
  4  5  6  7  8 11
  1  2  6 11 12 13