Yesterday I quickly glanced over all of the problems then spent a few minutes studing problem #1 without any success in figuring out the correct move and thought "this is a bit tough for me, better come back when I have more time."
Today I started at the botom with # 6 and found 18-14 to be the winning move, followed by 24-27, 22-18, 13-17, 18-15, 17-22, 21-17, 27-31, 17-13, 31-27, 14-10, at his point
black will lose the man on square 6 no matter where he moves and white will win.
I next glanced at #5 and then skipped up to Problem # 4, I really like this one! 27-23, 20X24, 23-18, very interesting.....
Many thanks to you Alex.
CHECKERS: The Mind Sport of Kings and Ordinary Men.