### Errata for "A Walk Through Combinatorics"

- Page 93, last line. Change "side" to "size".

- Page 136, line 3. Change
*D*_{n} to
*D(n)*.

- Page 170, Exercise 26. The recurrence should hold for
*n*
greater than or equal to 0 (not 1).

- Page 170, Exercise 32, line 2. Delete the word "form" at the end
of the line.

- Page 192, line 16. Change
*h*_{k} to
*h*_{j} (two times).

- Page 192, line 8-. Change
*G* to *T*.

- Page 194, Figure 9.8. This figure does not match the description
in the text describing it. One way to fix it is to relabel
*E, F,
G, H* as *A, C, B, D*, respectively.

- Pages 195-196. The statement that graph isomorphism is
NP-complete is not known to be correct. It is a famous open
problem.

- Page 196, line 7 of Notes. Change "Pitten" to "Pittel".

- Page 200, Exercise 31. Assume that
*k*>1.

- Page 200, Exercise 32. Change
*X* and *Y* to *x* and *y*, and change
*d*_{z} to *d*_{y}.

- Page 221, Definition 10.3, and many subsequent places. The term
"incidence matrix" is usually used instead of "incidency matrix".

- Page 229, Exercise 22. The statement of this exercise is somewhat
ambiguous. The statement should be that all longest paths
cross in
**at least** one
vertex.

- Page 243, line 3-. Change "minimal" to "maximal".

- Page 258, line 4. Replace
*p*(-1) by
(-1)^{t}p(-1), where *t* is the number of
vertices of *G*.

- Page 278, Supplementary Exercise (11). It should be assumed that
*V* is at least 3.

- Page 279, solution to (1). First,
*L* should be
*F*. More significantly, the reasoning and formula are
incorrect. Correct reasoning gives *F* = *E* +
*2k* - *V* - *(k-1)* = *E* - *V* +
*k* + 1.

- Page 283, Example 13.1. The phrase "three of them who do not know
each other" is ambiguous. Does it mean "three of them for which no two
know each other" or "three of them for which some two do not know each
other"? The former is intended. (If the latter, then the stated result
is a tautology.)

- Pages 401-402. Reference numbers are missing (ranging from 1 to
26).