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TAUTOLOGIES NP-Complete Condition

The decision problem TAUTOLOGIES is, Given $\forall x_1 \forall x_2 ... \forall x_n$ $\phi(x_1, x_2, ... x_n)$ a set of universally quantified Boolean variables and a Boolean formula ...
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35 views

Proof that such a Turing machine cannot be constructed…

Prove there can be no Turing machine $M^*$ that takes input $n$ and: i. halts printing 1 if $M_n$ halts on input 1 ii. halts printing 0 if $M_n$ doesn't halt on input 1 Intuitively I can see why ...
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27 views

What is the Church-Turing thesis?

Every source I look at online says something vague about Church's notion being equivalent to Turing's, but what exactly is the Church-Turing thesis? As I understand, it attempts to precisely define ...
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262 views

Turing Machine question, this is NOT HW

I was having a hard time understanding and solving this question that wants me to show the final tape and figuring out if whether or not the turning machine accepts it or not. I have a list of 20 ...
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3answers
2k views

Proving that a Turing Machine that only accepts even length strings is undecidable

I need to prove that a Turing Machine that only accepts even length strings in undecidable. The proof I was thinking is explaining the following: Given an input that contains even length strings, if ...
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1answer
138 views

Proving a language is Turing recognizable

Turing Machine M with a wait option has the option to make the machine's head wait where it is, until a case comes along where ...
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1answer
103 views

Where is the flaw in the following proof?

Where is the flaw in the following proof, that if a language is Turing recognizable then we can enumerate it? Proof Let $TM1$ be a Turing machine for language $L$. We can create an enumerator $E$ ...