Cat in the Hat Comes Back

A children's book by Dr. Seuss, and the sequel to the cat in the hat. The cat in the hat, predictably enough, comes back, and proceeds to wreak more havoc in the lives and home of the two children from the first book.

My Combinatorial Algorithms professor (Jeff Erikson) told us in class one day that he was seriously considering putting this book on the Recommended Books list for class, to help us learn recursion.

At one point, the Cat in the Hat needs to clean up a big mess.  So, the Cat takes off his hat, and underneath his hat is another hat, a hat with a big "A" on it.  He takes off the "A" hat and underneath is a "B" hat.  He takes off the "B" hat, and there's a "C" hat...all the way down to "Z".  He finally takes off the "Z" hat, and underneath that hat is a little "Z" cat who uses "Voom" to do all the work.  Then, the "Z" cat gets back on the Cat's head, and the Cat puts back on all his hats.

Lo and behold, recursion!

Prof. Erikson, however, realized that he did not yet have tenure and thus didn't want to risk waking up one day to see "COLLEGE PROFESSOR TEACHING DR. SEUSS!" plastered on the front page of the New York Times.