# Nondeterministic Turing Machine for $L^*$

If $$T$$ is a Turing Machine that accept a language $$L$$, I want to define a Turing Machine $$T'$$ such that accepts the language $$L^*$$.

An approach:

• $$T'$$ is a nondeterministic Turing Machine which has many tapes.
• $$T'$$ 'copies' in a nondeterministic way a prefix from the original string to another tape and then it is applied $$T$$

So well, what I should know is:

1. How many tapes has $$T'$$ ?
2. What happens next if $$T$$ accept this prefix
3. How is this prefix selected?
4. What is the end condition to accept a string in $$L^*$$.
• Could you write a program for recognizing $L*$ in your favorite programming language, if you had a subroutine for recognizing $L$? – D.W. Jun 23 '20 at 4:03
• @D.W. I'm pretty sure that I am – Eric Toporek Jun 23 '20 at 4:28
• I suggest you edit the question to describe how you'd do that, then figure out how to implement that in a Turing machine only after you've done that. A Turing machine is just a clumsy programming language. – D.W. Jun 23 '20 at 5:14