The cat needs the cow. The cow chases the tiger. The mouse needs the cat. The tiger is nice. If something chases the cow then it is blue. If something chases the mouse then the mouse chases the cat. If something is blue and nice then it needs the mouse. If the mouse is nice and the mouse is round then the mouse is red. If the cat needs the cow and the cat sees the cow then the cat sees the tiger. If something needs the cow and the cow sees the cat then the cow sees the tiger.
The cat does not need the cow.