Undecidability of the Emptiness Problem for Turing Machines
This paper demonstrates that the E_TM problem, which asks whether a Turing machine's language is empty, is undecidable. The proof involves assuming decidability and deriving a contradiction by constructing a decider for the known undecidable A_TM problem.

Easy Theory
23.7K views • Jan 18, 2021

About this video
Here we show that the E_TM problem is undecidable. We suppose that it were decidable, then construct a decider for the A_TM problem, which cannot possibly exist. The key idea is to make a new machine that has empty language iff M accepts w.
What is a Turing Machine? It is a state machine that has a set of states, input, tape alphabet, a start state, exactly one accept state, and exactly one reject state. See https://www.youtube.com/watch?v=j0bIxPqlYLE&ab_channel=EasyTheory for more details.
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What is a Turing Machine? It is a state machine that has a set of states, input, tape alphabet, a start state, exactly one accept state, and exactly one reject state. See https://www.youtube.com/watch?v=j0bIxPqlYLE&ab_channel=EasyTheory for more details.
Easy Theory Website: https://www.easytheory.org
GoFundMe: https://www.gofundme.com/f/easy-theory-video-studio
Patreon: https://www.patreon.com/EasyTheoryYT
Fourthwall: https://easy-theory-llc-shop.fourthwall.com
Problem Solving channel: @easytheoryprobsolve
If you like this content, please consider subscribing to my channel: https://www.youtube.com/channel/UC3VY6RTXegnoSD_q446oBdg?sub_confirmation=1
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Video Information
Views
23.7K
Likes
417
Duration
9:00
Published
Jan 18, 2021
User Reviews
4.6
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