In this question we will use the sentences you wrote in Exercise 9.9 to answer a question using a backward-chaining algorithm.

a. Draw the proof tree generated by an exhaustive backward-chaining algorithm for the query 3 h Horse (1%,) where clauses are matched in the order given.

b. What do you notice about this domain?

c. How many solutions for h actually follow from your sentences?

d. Can you think of a way to find all of them? (Hint: You might want to consult Smith et al. (1986).)