27 ≤ C(23,12,4) ≤ 31

Method of Construction: simple construction: deleted element from c(v+1,k,t) covering

Lower Bound: Schonheim

  2  3  4  5  7  9 10 15 17 19 20 23
  1  2  7  8  9 10 11 12 16 17 18 20
  2  3  4  5  6  9 11 13 16 18 20 23
  2  4  6  8 10 11 14 15 18 19 22 23
  1  2  3  4  6  7 11 12 14 15 18 20
  1  2  4 10 12 13 15 16 18 19 21 23
  3  6  8  9 12 13 14 17 18 19 21 23
  2  5  9 13 14 15 16 18 19 20 21 22
  2  4  5  7  8 13 14 16 17 18 22 23
  1  3  4  5  6  9 13 14 15 16 17 21
  1  5  6  7  9 10 12 13 15 18 22 23
  1  2  3  4  7 12 13 14 15 17 19 22
  1  2  3  5  6  7  8 14 16 19 20 23
  1  2  4  5  6  7  9 11 12 17 21 23
  5  7  8  9 10 11 12 14 15 16 21 23
  1  2  3  4  8  9 12 14 20 21 22 23
  2  3  5  7  8 10 11 12 13 19 20 21
  1  3  6  8  9 11 16 17 19 21 22 23
  3  5  7 11 12 13 18 19 20 21 22 23
  1  2  5  6  8  9 11 12 13 15 19 20
  1  3  8 10 11 13 14 15 17 18 20 23
  2  3  6 10 12 15 16 17 20 21 22 23
  1  3  4  5  7  9 10 11 14 18 19 21
  2  6  7  9 10 11 13 14 17 20 21 22
  1  3  4  5  8  9 11 12 15 17 18 22
  1  3  4  7  8 11 13 15 16 20 21 22
  1  4  5  6  8 10 17 18 19 20 21 22
  4  5  9 10 11 12 13 14 16 17 19 20
  3  4  6  7  8  9 10 12 13 16 19 22
  2  3  6  7  8 11 15 16 17 18 19 21
  1  2  3  5  6 10 11 12 14 16 18 22