theorem Th20:
  for k1,k2,k3,k4 being Instruction of SCM+FSA holds card( k1 ";"
  k2 ";" k3 ";" k4) =8
proof
  let k1,k2,k3,k4 be Instruction of SCM+FSA;
  thus card( k1 ";" k2 ";" k3 ";" k4)
     = card (k1 ";" k2 ";" k3)+ 2 by SCMFSA6A:34
    .= 6 + 2 by SCMBSORT:23
    .= 8;
end;
