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Question abot Recursive\Recursively Enumerable Languages

  1. Apr 1, 2009 #1
    Note: If this is a wrong section please move this thread to it's appropriate section.


    How do I prove that Language L1[tex]\in[/tex] R?

    L1={<M>|L(M)[tex]\in[/tex]RE}

    ( M is a turning machine, <M> is machine's encoding)
    I have the answer but i don't understand it!
    The answer goes like this (sorry for loose translation):
    Because of the fact that L(M)[tex]\in[/tex]RE, L1 contains all the encodings of the turning machine.
    We can build turning machine M that decides L1 language:
    On a given input string X we check if it's comprise an encoding of some machine, if it's M stops.



    First of all I don't understand the conclusion that "L1 contains all the encodings of the turning machine"
     
  2. jcsd
  3. Apr 1, 2009 #2

    HallsofIvy

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    First the term is "Turing machine", not "turning machine". It is named for the British mathematician, Alan Turing.

    "[itex]L_1= {<M>|L(M)\in RE}" says that [itex]L_1[itex] is the set of such encodings.
     
  4. Apr 1, 2009 #3
    And if i was L1={<M>|L(M)[tex]\in[/tex]R} ?
     
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