[Retros] Challenge

andrew buchanan andrew at anselan.com
Tue Dec 1 14:14:30 EST 2009

Hi Joost,

Thanks for picking this up. The diagram was wrong (sorry), but in trying to repair it I have found a better position:

"#1", "#2", "#3", "#4", "#5", "#6", "#7"

I am aware there should be no short mates in an exact directmate, and that a Tablebase does not pick these up. But Juha has deliberately left the precise terms of the challenge vague.
Maybe this is to foment discord amongst us :o) but I think it's because
he thinks that accidental new interpretations may be fruitful.

He said he used a Tablebase and he said in a separate email to me that he has found a solution n>10 !?! If so, I think it is highly unlikely that he has excluded short mates. If in fact his position does exclude short mates, I am very impressed.

Perhaps Juha can clarify what his position is on short mates in his challenge?

The "infinite challenge" that was discussed earlier is different. Here White can *force* a mate in exactly k moves, for each k. Again short mates may exist *but* White can avoid them.

All the best,

----- Original Message ----
From: Joost de Heer <joost at sanguis.xs4all.nl>
To: retros at janko.at
Sent: Tue, December 1, 2009 3:50:36 PM
Subject: Re: [Retros] Challenge

> 4k3/8/5K2/8/8/6N1/3Qpb2/8

> "#1", "#2", "#3", "#4", "#5"

How does white deliver mate in 1, 2, 3, 4 or 5?

And TB results can't be trusted for exact-# compositions. The move that is indicated #4 may have a defensive move which leads to a #3, which isn't allowed in an exact-# composition, all variations should be of the same length.

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