1. Turing Machines – Examples Lecture 24 Section 3.1 Wed, Oct 17, 2007

2. Turing Machine as Language Processor Design a Turing machine that will shift the input string one space to the right, leaving a blank in the leftmost cell.

3. Strategy Strategy: Read the first symbol and write a blank. Move right. Read the second symbol and write the first symbol. Move right. Read the third symbol and write the second symbol.

4. Strategy Move right. Continue in this way until a blank is read. Write the last symbol.

5. The Turing Machine q0q0 acc 0  _, R 1  _, R 0  0, R 1  1, R 1  0, R 0  1, R _  0, R _  1, L  _  L _  R

6. Another Language Processor Design a Turing Machine that will duplicate the input string. Replace w with w#w.

7. Turing Machine as Calculator Design a Turing Machine that will add 1 to the input. For example, if the input is 100111, the output will be 101000. Design a Turing Machine that will subtract 1 from the input.

8. Turing Machine as an Enumerator Design a Turing Machine that will print on its tape all binary strings. Design a Turing Machine that will print all binary strings that contain an even number of 0s and an odd number of 1s.

9. Turing Machine as an Enumerator Design a Turing Machine that will print all binary strings all of whose prefixes contain at least as many 0s as 1s (balanced parentheses).