Difficult or easy, that is the question December 27, 2007
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"Please make next problems harder," wrote Paul Leyderman from Chicago, USA. "When one solves a problem in a couple of minutes it's just boring." On the other hand Piotr Pisanski of Chatham, Canada wrote: "Every year I look forward to these puzzles, so let me begin by saying thank you. I'm rated roughly 1700, and I do puzzles once a year (here). I'm in the middle of figuring out the first series self mate, and I can't stop thinking that 'even an amateur' should be able to solve this one. And then the next puzzle is 'slightly harder'. Please stop making them sound so damned easy, because you're turning off many amateurs from these puzzles. It is great when you indicate something is hard, because then I feel good when/if I solve it. But when you introduce a puzzle as 'easy' or 'obvious', I lose interest because I do not want to spend 10-20-50 minutes solving something you feel is easy."

Difficult or easy, that is the question. Whether 'tis nobler in the mind to present really easy, motivational material, and draw the dissatisfaction of Paul, or to take heed of the very valid points Piotr makes and try to get as wide an audience interested in – or even better: hooked on – the world of chess puzzles. We'll have to find a middle path.

After yesterday's more or less easy series helpmates we give you a more difficult one, sent to us by that supreme problematist John Nunn.

Jacob Mintz, Prize, Ideal-Mate Review 2000

Series helpmate in 21

For those of you who found yesterday's explanation of this type of problem too dry John has written it up as a little dialogue between two chess enthusiasts.

“Looks like an easy win for White”, I remarked.

“Maybe you won’t find it so easy when I explain what you have to do”, commented my friend.

“Oh, what’s that?”, I asked suspiciously.

“Well, Black has to play 21 moves in a row, without White moving at all, in order to reach a position in which White can mate in one move.”

“Um ... like one of those helpmate things.”

“Yes, but with only Black moving, except for White’s mating move at the end. And there’s one other thing you have to know – Black isn’t allowed to give check, except possibly for his final move.”

“Perhaps I should try to work out the mating position first, and then work out how to get there.”, I suggested.

“That might be a good idea.”

Twenty minutes later I had the answer.

Do not give up on this problem, or believe the 21 moves are too daunting. Before you give up on it, here are some hints. Don't read them if you wish to experience the full challenge of solving the problem.

You should, as John has indicated, try to define the mating move first. Knight to c7 will never mate Black as he has KxPb6. Of course Black could try to put a blocking pice on b6, which would have to be a rook (a black knight on b6 would be giving check). But then of course the white pawn on a7 would be undefended and Nc7 would not work.

We are going to find a different mate. This can only be axb8 and a promotion to – a knight! This is a mate if there are black pieces on a5 and b5 to block the retreat of the king. So all you have to do is to find a way to get two black pieces there. They have to be promoted pawns. The third promoted piece has to sacrifice itself on b8. All of this has to be done without illegal moves, e.g. putting the white king into check (except on the final move). And you should also remember: in a problem like this every single move and the move order has to be unique. Astonishingly, it is.