Chess category

Photo credit: Rob Roy.
Used under this licence.

In response to Graham Pointon’s query about solutions to chess problems on this site, I have created a new category for chess. I think I have now put a solution in the comments to all the relevant posts. Please let me know if you come across any I have missed.

Check check

You can’t get very far in learning to play chess without understanding what check means. So for someone like me, who has been playing on and off for 55 years or so, you would think the concept is simple.

If an opponent’s piece attacks your king, move it. If you can’t, or if you can only move to another square which is also attacked by a piece of your opponent’s, then it’s checkmate.

I played chess this week and the first game came down to the position shown above. Actually, there were more pieces on the board, but they are irrelevant to this little tale, so I’ve left them out.

It’s easy to see that white (me!) is in big trouble. But is that true? Can the white king take the black queen? I didn’t know, but my opponent (JDL) was sure that that would be illegal, because the white king would then be in check from the black rook. BUT the black rook can’t move. It is pinned to the king by the white bishop. If it moves, then the black king is in check! WHEW!

To my chagrin it turns out that JDL is right. Here is Article 3.9 of the rules of chess as determined by the Fédération internationale des échecs:

The king is said to be ‘in check’ if it is attacked by one or more of the opponent’s pieces, even if such pieces are constrained from moving to that square because they would then leave or place their own king in check. No piece can be moved that will either expose the king of the same colour to check or leave that king in check.

The very next rule (4.1) is puzzling. It states that:

Each move must be made with one hand only.

I have no idea why.

The Légal Trap

The chess position above is an example where the Légal Trap can be played. This is named after Sire Légal (1702-1792), a French chess player whose full name was François Antoine de Legall de Kermeur. It is White’s move and the first move of the trap seems like a monumental blunder. It is f3xe5, which exposes White’s queen and the knight moved.

Can you see the trap?

1 … g4xd1 2 c4xf7+ e8e7 3 c3d5 checkmate.

Even if Black sees the trap and plays 1 ……. d6xe5, White can reply with d1xg5 and is a pawn up.

Al Adli’s chess problem

This chess problem is about 1,000 years old and was supposedly devised by someone called Al Adli. I have no information about this character, but whoever it was, the problem has a fine, elegant solution.

As you can see, Black, whose turn it is to play, is in dire trouble. White can play either Ra1 or R (either of them)-b2 and it’s curtains for Black. How can Black survive and in fact win? See comments for solution.