Prove the cases in the progress lemma for sums and the preservation lemma for products. The rules for products and sums can be found in the notes for lecture 10. As usual, state, but do not prove, the inversion and/or canonical forms lemmas you will need.
Either hand your assignment in in class, or else place it as hw03.pdf if in the directory /afs/andrew.cmu.edu/course/15/814/handin/**YOUR ANDREW ID**/ by midnight on Wednesday.