Sunday Chess Problem

My SIWOTI syndrome has not returned, the end of the semester notwithstanding. Watching the daily broadcasts from the recently completed U. S. Chess Championship, however, has certainly gotten my chess juices flowing. So here's another installment of Sunday Chess Problem!

Another mate in two for you this week, but with a twist. The problem below was composed by Norman Macleod in 1984. In the position below, white is to play and mate in two. The twist is that this game is being played under Madrasi rules!

Here's how it works: Everything proceeds as in regular chess, but with one additional rule. When like pieces of opposite color observe each other, they become paralyzed. They cannot move. At all. That might sound a bit weird, but this problem is a crystal clear example of how it works.

The key move is 1. Nb4!

You'll notice that I did not put the little “+” sign after that move, which indicate a check. That's because black is not in check right now. The white knight is currently paralyzed, because it is observed by the black knight on d5. (The black knight is also paralyzed, of course.)

White's key move does introduce a threat, however. If left unimpeded, white will play 2. Qxd5 mate:

Capturing the black knight unparalyzes his white counterpart, and suddenly black is in check. Mate, actually.

You might have noticed, however, that white has two other ways of capturing the black knight on d5. Why, then, did I not say that white has three threats? Well, let's have a look. If white tried to play 2. Bxd5 we would reach the following position:

Black is certainly in check. But the white bishop is now paralyzed on d5, since it is observed by the black bishop on g8. (And, again, the black bishop is paralyzed too.) That means that the black king has suddenly picked up a flight square on b3. Therefore, this is not mate.

Do you see the problem if white tries 2. Rxd5 mate?

This time it is the white rook that paralyzes itself on d5, meaning that the black king now has a flight square on d2. So, even though white has three ways of taking the knight, he only has one mate threat.

Incidentally, in that last line I gave white's move as 2. Rxd5 mate. But since white has two rooks that can reach d5, should I not have written 2. Rdxd5? Certainly not! The white rook on c5 is paralyzed by the black rook on c8. So that rook cannot move. Of course, that state of affairs could change...

Back to the action. Since one threat is all you need, black needs to find a defense. He only has one basic strategy. He can move his queen to a square that observes d5. In this way, when the white queen arrives on that square she will paralyze herself. As a result, black will be able simply to take the rook on d1. Black has three ways to carry out this basic idea.

Option one: Black plays 1. ... Qe6. Sadly, this interferes with his bishop on g8, meaning that white can now play 2. Bxd5 mate after all:

Option two: Black plays 1. ... Qd6. This time black has interfered with his own rook, and white gets to play 2. Rxd5 mate:

Which leaves just one more try. Option three: Black plays 1. ... Qc6. This time we have a new effect. Black has now interfered with his rook on c8. That unparalyzes white's rook on c5, which makes it possible for him to reply with 2. Rcxd5 mate:

Very cool stuff. This is our first example in this series of what problemists refer to as “fairy chess.” Chess composers have devised an extraordinary variety of alternate rules and novel chess pieces, and as this series progresses I shall try to feature other forms for you. For the most part, these fairy genres are not really intended as rules that should be employed when actually playing a chess-like game. I don't know how much fun it would be to actually play a game under Madrasi rules, but that is hardly the point. Chess composition is about showing an artistic effect, and hopefully about provoking a smile from the solver. I'd say this problem does that rather well, wouldn't you? Objecting that a composer has employed an exotic set of rules is like criticizing a painter for not perfectly reflecting reality in his work.

See you next week!