I had to look at the domain twice to make sure I was seeing it correctly. I grew up in Richmond and VCU (Virginia Commonwealth University) is overwhelmingly known as a great art school; its other disciplines are seen as average at best.

To see a mathematics textbook from VCU appear on Hacker News was a welcome sight indeed!

I was also excited to see VCU on HN. VCU has come a long way from were it was 20 or 30 yrs ago.

Though, it's still a great art school.

Not free, but don't forget Polya: http://www.amazon.com/How-Solve-Mathematical-Princeton-Scien...

This is a very nice book.

Useful resource. It doesn't stress enough the value of direct proofs for intuition enough to my liking.

Example: in section 6.4, it is easy to prove that 6a^2-2a+7 is even iff a is odd, and the direct proof gives a better intuition that the proof by contradiction and contrapositive proofs described.

Also, "Mathemathics for Computer Science" course from the MIT has a very nice introduction on proofs. Excellent book: http://news.ycombinator.com/item?id=1935049