# CMPSCI 250: Introduction to Computation

### David Mix Barrington

### Fall, 2004

# Homework Assignment #5

#### Posted Friday 29 October 2004

#### Due on paper in class, Friday 5 November October 2004

#### Problem 5.4.2 corrected 1 November 2004.

#### Problem 6.4.1 corrected 4 November 2004.

There are nine questions for 100 total points.
All are from the textbook, *A
Mathematical Foundation for Computer Science*, from the green (4-5)
and yellow (6-7) volumes.
"Problem 1.1.2", for
example, refers to Problem #2 in Section 1.1, and similarly. Make sure
you don't do an Exercise when a Problem is assigned!

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

- Page 5-10: Problem 5.2.4 (10)
- Page 5-15: Problem 5.4.2 (10) Correction: The statement
you are asked to prove in the text is false. (For example, let S = aa and T = aaaa.)
Instead, please prove the following for a one-letter alphabet: If S and T are any
regular expressions, then (S+T)
^{*} = S^{*}T^{*}.
- Page 5-22: Problem 5.5.1 (15)
- Pages 6-8 and 6-9: Problems 6.1.2 (10) and 6.1.5 (10)
- Page 6-14: Problem 6.2.1 (10)
- Page 6-18: Problem 6.3.4 (15)
- Page 6-23: Problem 6.4.1 (10) Correction (4 Nov):
The "j-k falling" at the very end of the problem should read "k-j falling".
- Page 6-33: Problem 6.6.3 (10)

Last modified 4 November 2004