MIT 18.404J Theory of Computation, Fall 2020 Instructor: Michael Sipser View the complete course: https://ocw.mit.edu/18-404JF20 YouTube Playlist:    • MIT 18.404J Theory of Computation, Fa...   Quickly reviewed last lecture. Discussed the reducibility method to prove undecidability and T-unrecognizability. Defined mapping reducibility as a type of reducibility. Showed that emptiness problem for TMs is undecidable and T-unrecognizable. License: Creative Commons BY-NC-SA More information at https://ocw.mit.edu/terms More courses at https://ocw.mit.edu/ Support OCW at http://ow.ly/a1If50zVRlQ We encourage constructive comments and discussion on OCW’s YouTube and other social media channels. Personal attacks, hate speech, trolling, and inappropriate comments are not allowed and may be removed. More details at https://ocw.mit.edu/comments.