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2.C: Non-deterministic Turing machines and their equivalence to ordinary Turing machines

Course week(s) Week 2
Course subject(s) 2: Turing Machines and the Church-Turing Thesis

Description: The notions of decidability and recognisability for non-deterministic Turing machines are defined. König’s Lemma is explained and its use is shown in the proof of the computational equivalence of non-deterministic Turing machines and ordinary Turing machines. It is argued how non-deterministic Turing machines for solving a specific problem can be constructed by breaking up the problem in first guessing a solution and then checking its validity.

Book: Introduction to the Theory of Computation, Chapter 3, pp. 152-154.

Exercise: see slide 18 of this lecture

Key concepts:

  • Nondeterministic Turing Machines
  • Equivalence TMs and NDTMs
Module 2C
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