lower bound = 5

C(7,6,4) = 5

Method of Construction: lex covering

Lower Bound: Schonheim

  1  2  3  4  5  6
  1  2  3  4  5  7
  1  2  3  4  6  7
  1  2  3  5  6  7
  1  2  4  5  6  7