See the problem sets section. There has been a slight correction to problem 5 of problem set 1. Problem Set 1 has been released. See the problem sets section. Look at this typical reduction to help with your homework, and your skills at showing problems are not decidable.
L is now available, and includes an inductive proof of the correctness of the construction.
Inductive proof of closure of regular languages under inverse homomorphism, for your viewing pleasure. This template for doing pumping lemma proofs provides the English and logical glue to bind together your pumping lemma argument. Problem set 1 has been released. The inductive proof of the lemma discussed in class is now available. Text Errata , including new ones found by you.