22 April 2011

Again no diagrams

In previous posts, I wrote about proof games. There, you have a diagram together with the stipulation to reach this position after a given number of moves. Of course, these moves (i.e. their order) are unique.

Lately, I read about chess puzzles dealing with sort of an extension/variation of this — not having a diagram. They ask to find a position that meets a certain goal and for which there is a unique proof game in the given amount of moves. I am sure, you've already seen such puzzles. There are several (sub)types and the French problemist Alain Brobecker has collected/classified lots of them.

The first type are games to be found that are uniquely determined by the last move. An example (puzzle #1): Find the game ending with 4. - b5# (François Labelle). In 2003, the Canadian problemist François Labelle wrote a computer program allowing to find such games having up to 11 half-moves.

In another type, you are only allowed to make moves with the white pieces (a seriesmover). Labelle's program can also handle that. The second puzzle is this: Find the series of White moves ending with 6. exf8=R# (François Labelle).

Finally, there is a third and most challenging type. These tasks just describe a certain theme that is to be realized within the given number of moves by a unique proof game. Here is puzzle #3 for you (author unknown): Find a position with unique realization in 2.5 moves ending with the mate of the black king. Three solutions.

1 1. d4 c6 2. Kd2 Qa5+ 3. Kd3 Qa3+ 4. Kc4 b5#
2 1. d4 2. d5 3. d6 4. dxe7 5. Qd6 6.exf8=R#
3 Originally, Alain only gave one solution, but already mentioned there was another one: 1. e4 f5 2. exf5 g5 3. Qh5#. As you can see, the mate after 2.5 moves as such can be achieved by various ways. But, the challenge is to find a final position which has a unique move order that leads to it. Therefore, e.g., the position after 1. e4 f5 2. e5 g5 3. Qh5# is not allowed, as you also could arrive there after 1. e4 g5 2. e5 f5 3. Qh5#.
I took up the challenge and searched for the second solution. Finally, I managed to crack the puzzle. In fact, I found even two more solutions (though not really different)! 1. e3 e5 2. Qh5 Ke7 3. Qe5# and 1. e4 e5 2. Qh5 Ke7 3. Qe5#.


HeinzK said...

I think 3. Qxh5# is actually called the idiots' mate :)

bernoulli said...

You're the first to call it that way. At least, Google (nor me) doesn't know it. - Anyway, is that actually important?! No.

HeinzK said...

It is VERY important. There is the fool's mate, the idiots' mate and the scholar's mate. All these games are a major part of any chess player's archives :-)

bernoulli said...

WHO calls it idiots' mate - except for you?? Show me the reference.

This name (or others like opening names, etc.) is definitely NOT important for problemists, especially not for the topic I was writing about!

HeinzK said...

I call it the idiots' mate, so from now on it will be the idiots' mate. Does it matter if other people have called it this way before on the Interweb? And if my reference would be that chEckmAtIngurpAwnz on the chessfornewbies.com forum has called it the idiots' mate - would you accept that as a solid reference? :-D

bernoulli said...

OK, that's it. It's simply enough. This was the last comment by you that is published.

Look at the "logic" with regards to the idiots' mate:
1) "is actually called..."
2) "It is VERY important. ..."
3) "I call it the idiots' mate, so from now on it will be the idiots' mate."

Please, troll elsewhere.

Cornel said...

François Labelle is actually Canadian.

bernoulli said...

Thank you for the info!