The cow is blue. The cow does not need the tiger. The dog chases the cow. The dog eats the cow. The dog eats the tiger. The dog is cold. The dog is green. The dog is young. The dog does not need the cow. The tiger does not need the cow. If something needs the dog and it is green then the dog chases the cow. If something needs the cow and the cow eats the dog then the cow chases the dog. If something is green then it needs the tiger.
The tiger needs the dog.