A dog meant that Liam needed to walk .
dog ( x _ 1 ) AND mean . agent ( x _ 2 , x _ 1 ) AND mean . ccomp ( x _ 2 , x _ 5 ) AND need . agent ( x _ 5 , Liam ) AND need . xcomp ( x _ 5 , x _ 7 ) AND walk . agent ( x _ 7 , Liam )