From one corner to the other, boxers chase their opponents, hoping to land the winning blow. The fighter above seems ready to come out of her corner and do whatever it takes to lay out her opponent.

But some fighters win by decision rather than the quick knockout. That fact, and the title of today's column, provide broad hints toward the solution of the problem shown below.

WHITE

BLACK
Black to Play and Win

B:W31,29,12,K2,K1:B22,K15,K14,K10,3.

Before you begin, let's make note of a couple of things. First, White has two kings more or less entrapped in or near the Black double corner. Second, White has a man on 12 that is immobilized. Finally, White holds a bridge position on 29 and 31, but the man on 29 is immobile, and if White moves the man on 31, Black can stop it with 15-19 and then win it a few moves later.

So what can White do? Not much except perhaps shuffle around in the double corner. Black has a tremendous mobility advantage. That usually spells a win. The question is how to make it happen.

We'll repeat our hints. This is not a quick knockout; to win, Black must patiently apply technique. And again, keep in mind the title of our study. It's by no means an easy fight. This one is championship class.

Don't let this one knock you out; win the decision, then land your mouse on Read More to check your solution.

Solution

The fight indeed goes the full 15 rounds. Variations in the solution are of course possible.

Avoiding a trade.

White of course still wishes to eschew a trade. But that can no longer be accomplished.

The white king has changed corners, hence our problem title.

The trap is closing.

Black Wins.