If Bonnie bellows, then Keiko cackles
If Keiko cackles, then Sheila does not shout
If Bonnie does not bellow or Keiko does not cackle, then Sheila shouts
Sheila shouts, and if Bonnie bellows, then Keiko cackles
It is not true that Sheila shouts if Bonnie bellows
If Bonnie does not bellow, then Keiko cackles and Sheila shouts