Full Theory of Computation Lecture playlist: https://www.youtube.com/watch?v=OPaB-rpKhZ0&list=PLylTVsqZiRXMiTARmrsxCWU2RahyKB_Ae&index=1&t=1s Lecture "a la carte" playlist: https://www.youtube.com/watch?v=gO9Ho9Dpu8k&list=PLylTVsqZiRXP51EfJWv8cxD6wIFTZQD9_&index=1 Here we go over the notion of what a "simple" computer is, and how to simplify our notion of a computer. We think of what a "state" of a machine is in, and how these states relate together via "transitions." We think of other useful properties for such machines and how to abstract the details away to say something more general. Easy Theory Website: https://www.easytheory.org Become a member: https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg/join Donation (appears on streams): https://streamlabs.com/easytheory1/tip Paypal: https://paypal.me/easytheory Patreon: https://www.patreon.com/easytheory Discord: https://discord.gg/SD4U3hs #easytheory Youtube Live Streaming (Sundays) - subscribe for when these occur. Social Media: Facebook Page: https://www.facebook.com/easytheory/ Facebook group: https://www.facebook.com/groups/easytheory/ Twitter: https://twitter.com/EasyTheory Merch: Language Hierarchy Apparel: https://teespring.com/language-hierarchy?pid=2&cid=2122 Pumping Lemma Apparel: https://teespring.com/pumping-lemma-for-regular-lang If you like this content, please consider subscribing to my channel: https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg?sub_confirmation=1 ▶SEND ME THEORY QUESTIONS◀ ryan.e.dougherty@icloud.com ▶ABOUT ME◀ I am a professor of Computer Science, and am passionate about CS theory. I have taught many courses at several different universities, including several sections of undergraduate and graduate theory-level classes. ... https://www.youtube.com/watch?v=gO9Ho9Dpu8k

Here we show that deterministic context-free languages (DCFLs) are not closed under concatenation. The idea is to have two languages whose concatenation is the complement of {a^n b^n c^n : n at least 0}, which is not a DCFL. A deterministic context-free language is the language of a deterministic pushdown automaton (DPDA). The essential idea is that a DPDA is equivalent to a PDA, except that there can only be one "choice" of transition from any state on any input, with anything on the stack. See https://www.youtube.com/watch?v=GzR5FiiIogY&ab_channel=EasyTheory for more details. Easy Theory Website: https://www.easytheory.org Become a member: https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg/join Donation (appears on streams): https://streamlabs.com/easytheory1/tip Paypal: https://paypal.me/easytheory Patreon: https://www.patreon.com/easytheory Discord: https://discord.gg/SD4U3hs #easytheory Merch: Language Hierarchy Apparel: https://teespring.com/language-hierarchy?pid=2&cid=2122 Pumping Lemma Apparel: https://teespring.com/pumping-lemma-for-regular-lang If you like this content, please consider subscribing to my channel: https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg?sub_confirmation=1 Gold Supporters: Micah Wood Silver Supporters: Timmy Gy ▶SEND ME THEORY QUESTIONS◀ ryan.e.dougherty@icloud.com ▶ABOUT ME◀ I am a professor of Computer Science, and am passionate about CS theory. I have taught many courses at several different universities, including several sections of undergraduate and graduate theory-level classes. ... https://www.youtube.com/watch?v=qGOw0n9gJR4