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Lec10 - VARIANTS OF TURING MACHINES Notes by Jordan Ganoff...

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VARIANTS OF TURING MACHINES - 2/23/05 Notes by Jordan Ganoff and Niel Stuver Multitape Turing Machines Standard Turing Machine (STM) Multitape Turing Machine (MTTM) MTTM STM Steps to convert: 1. Place dots and extra tape squares separated by # 2. Let S be an STM: a. S scans tape for all symbols at tape head positions b. S makes a second pass to update the tape 3. If S moves onto a #, make this square blank and copy each subsequent square over to the right one spot MTTMs can now be used in place of STMs for homework and further proofs. Nondeterministic Turing Machines δ: Q x Γ → P( Q x Γ x {L,R} ) k – 1 tapes input tape k tapes δ: Q x Γ k → Q x Γ k x {L,R} k input tape: a b c a a a b -- -- a b c a a b represent tape heads a b c a a b # a b -- -- # a a # a b c # Σ = { a, b, c } Γ = { a, b, c, --, a, b, c, --, # }
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For a string to be accepted there must exist a computation path that leads the machine into q accept . Standard Turing Machine (STM) Nondeterministic Turing Machines (NDTM) NDTM STM The NDTM can be simulated on a STM using a MTTM with 3 tapes.
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  • Spring '08
  • Staff
  • Non-deterministic Turing machine, Probabilistic Turing machine, multitape Turing machines, standard Turing machine

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