Typo at page 122: Chapter 3.1, Exercise 21

[MetallicCrimson]

In (c),
Proof. p is even, for some a prime number p.
contains an extra indefinite article, so it should be
Proof. p is even, for some prime number p.

Also, I think the commas in all four parts are not needed, so I'd write them as:

Proof. The total degree of G is even for any graph G.

Proof. The base angles of T are equal for any isosceles triangle T.

Proof. p is even for some prime number p.

Proof. f is not differentiable for some continuous function f.

(But that could only be me.)

[spamegg1]

Closed by #44 thanks a lot!