CMPSCI 250: Introduction to Computation

David Mix Barrington

Spring, 2011

Homework Assignment #9

Posted Thursday 21 April 2011

Due on paper to me or to CMPSCI main office by 4:00 p.m., Tuesday 3 May 2011

There are seven questions for 60 total points plus 10 extra credit. All are from the textbook, Mathematical Foundation for Computer Science. Note that the book has both Exercises and Problems -- make sure you are doing a Problem and not the Exercise with the same number. The number in parentheses following each problem is its individual point value.

Students are responsible for understanding and following the academic honesty policies indicated on this page.

Writing Exercise 2 of Excursion 14.9 corrected on 26 April 2011.

Exercise 14.10.2 corrected on 28 April 2011.

• Problem 14.8.1 (10)

• Problem 14.8.3 (10)

• Excursion 14.9, Writing Exercise 2 (10) Corrections: The final regular expression should be [λ + a + ba + aba]b^*. You may use state elimination to get the regular expression from the DFA even though that is in 14.10, after 14.9 -- you may also use any other valid method but please give some justification of your expression if you do not use state elimination.

• Problem 14.10.2 (10) The regular expression in question is given incorrectly in the solution to Exercise 14.10.3 in the book. It should be (b + ab^*ab^*a)^*.

• Problem 14.10.4 (10)

• Problem 15.6.2 (10)

• Problem 15.10.4 (10XC) Don't worry about details of Turing machines -- show that there is an algorithm that decides this language.

Last modified 28 April 2011