# CMPSCI 250: Introduction to Computation

### David Mix Barrington

### Spring, 2006

# Errata in the Textbook

Errors in the fourth draft of *A Mathematical Foundation for
Computer Science* (course packets #57, #??, and #??, Collective Copies) will
be listed here as they are discovered. My thanks to all who have
reported errors!

- Page 0-7, Schedule: The second midterm is on Thu 30 March, not "Thu 31
March".
- Page 1-14, Problem 1.2.2: The first line should be "Let A be any finite
alphabet, and let u and v be strings over A." No reference to the alphabet
of Problem 1.2.1 is intended.
- Page 1-23, Definition: The first "p" on the second line of the Definition
should be a "q".
- Page 1-35, longest formula in the middle of the page: There should be
a "not" sign in front of the last "x ∈ C".
- Page 1-40, footnote: In the third line the second "zero" should be "one".
- Page 1-47, "
**Proof By Cases**" formula: Parentheses are wrong --
one of the ")"'s after the ¬r should be moved to after the second q so
the whole formula is
(((p∧r)→q)∧((p∧¬r)→q))→(p→q).
- Page 1-48, Problem 1.7.1: In the fourth line, "he demands to have the
instance..."
- Page 1-52, second paragraph: Capitalize "If" after "
**Fantasy Rule:**"
- Page 1-53, Problem 1.8.4: On the third line it should say
"p
^{2}=2q^{2}" rather than "q^{2}=2p^{2}".
On the fourth line, the new proposition should be "p is even".
- Page 2-6, Problem 2.1.4: in the third line, it should say "...whose
second element is in B × C."
- Page 2-48, second line: "transitivity" is misspelled.
- Page 4-26, second line: should say "x + 0 = x".
- Page 11-9 (vol 1),
solution to Exercise 1.7.2 (d): The header line of the truth
table is wrong. The head of the fourth column after the vertical bar should be
"∧", and each column after that should have the header that is now on the
column to its left. Thus the formula being evaluated is
"((p∧q)∧r)↔(p∧(q∧r))".
- Page 11-22 (vol 1), solution to Exercise 3.3.3 (a): First number in first
equation should be 453, not 553.
- Page 11-23 (vol 1), solution to Exercise 3.3.3 (b): First number in first
equation should be 453, not 553.
- Page 11-28 (vol 1), solution to Exercise 3.9.1: second line, "greater
than 1 divided..."

Last modified 27 March 2006