More on Turing Machines.

• Example to see how TMs work: check that a string has 2n 0’s, for some n.

• Low-level pseudocode:

• M: On input string w:

  • Sweep left to right across the tape, crossing off every other 0.
  • If in stage 1 the tape contained a single 0, ACCEPT
  • If in stage 1 the tape contained an odd number of 0’s (but more than one), REJECT
  • Return he head to the left-hand end of the tape
  • Start over.

Previous slide

Next slide

Back to first slide

View graphic version