
Description: Quickly reviewed last lecture. Showed that \(\mathbb{N}\) and \(\mathbb{R}\) are not the same size to introduce the diagonalization method and used it to prove \(A_\bf{TM}\) is undecidable. Introduced the reducibility method to show that \(HALT_\bf{TM}\) is undecidable. Instructor: Prof. Michael Sipser