# Combinatorial Mathematics - Fall 2007 Typos

This page lists the typographical errors that have been discovered in the Fall 2007 pre-publication version of Combinatorial Mathematics, by Douglas B. West. This page is of interest only to those persons having a copy of this draft, particularly the students in my course, other users of the text, and reviewers. Please send comments and corrections on the book to west @ math.uiuc.edu. Contributors are noted in parentheses. Please do not send comments about incorrect page numbers in the index (and note that all page numbers there are odd for \TeX nical reasons); however, I do want to know of missing terms that should be added to the index.

## Category 1: Mathematical typos/corrections to text

• p30 - Exercise 1.1.43: The conclusion does not hold for all m. I believe it holds when m is prime.
• p87 - Lemma 2.2.16: The index of summation in the statement should be "n", not "k" (Sayan Dissanayake)
• p74 - Exercise 2.1.21: the first equation should not have the last term on the right (Art Benjamin)
• p95 - Exercise 2.2.26: "Fk" should be "Ak"
• p117 - Example 3.1.11: In the last line of the example, the factor xk is missing from both summands (Hsueh-Yi Chen)
• p128 - Exercise 3.1.30: "Sn" should be "S2n"
• p144 - Exercise 3.2.43: "3.2.23" should be "3.2.16"
• p204 - Theorem 4.1.31: In the figure, the subscripts for the vertices of Y on the right are wrong; \sigma'(3) and \sigma'(1) should be switched
• p368 - Exercise 7.1.22: "if a" should be "every"
• p422 - Exercise 8.1.23: the numerator should be the maximum of \delta(H)+1 over subgraphs H of G
• p479 - Exercise 9.1.20: delete "05F"
• p584 - Theorem 11.1.12: in the second line, the denominator should be 4, not 3
• p617 - Exercise 11.3.10: inside the floor function should be rs/(r+s-1)
• p952 - Theorem 17.2.15: the statement and argument are incorrect. The correct lower bound is the ceiling of \sqrt{n-1}, which is achieved by the polarity graph
• p953 - just after Proposition 17.2.16: the statement is not correct. The number of edges in the polarity graph is q(q+1)²/2, and it differs from the upper bound by q+1

## Category 3: Minor typos and corrections

Note: Corrections involving addition, deletion, or alteration of one punctuation mark may be implemented without being listed here. Corrections to capitalization may also be omitted.
• p73 - Exercise 2.1.16: "Caroll" should be "Carroll"

Archive of corrections to earlier versions: Fall 2006, Fall 2005, Fall 2004, Fall 2003, Fall 2002.