lower bound = 12

C(9,6,4) = 12

Method of Construction: lex covering

Lower Bound: Schonheim

  1  2  3  4  5  6
  1  2  3  7  8  9
  4  5  6  7  8  9
  1  2  4  5  7  8
  1  3  4  6  7  9
  2  3  5  6  8  9
  1  2  4  6  8  9
  1  3  5  6  7  8
  2  3  4  5  7  9
  1  2  5  6  7  9
  1  3  4  5  8  9
  2  3  4  6  7  8