Computer Chess Club Archives




Subject: Re: Mate the Royal Couple

Author: Heiner Marxen

Date: 14:39:02 11/15/98

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On November 14, 1998 at 10:37:55, Hans Havermann wrote:

>Valentin Albillo, more than a year ago, posted his "unsolved"
>3qk3/8/8/8/8/8/PPPPPPPP/RNBQKBNR w KQ - (Test #91:
><>). Computationally intensive,
>Albillo conjectured "it's a mate in 12". A number of chess engines had a go at
>it, but the attempts are old and seem dated. I wonder if this problem has since
>been solved.
>I thought I should let MacChess (5.0b3) try this on my 300 MHz G3. After 56
>hours, toward the end of 13-ply, MacChess came up with:
> 1. e4 Qd4
> 2. Bb5+ Ke7
> 3. Qg4 Qe5
> 4. Qd7+ Kf8
> 5. d3 Qh5

After 4. Qd7+ there are just two legal moves, Kf8 and Kf6.  Much to my own
surprise my problem solving program already found solutions for mate in 7
in both cases.  This would amount to a mate in 11, provided the moves
before 4. ...Kf8/Kf6 are already optimal (which I don't know).

After 4. ... Kf8, 5. d3 is the unique key starting a mate in 7, while
after 4. ... Kf6, the following three moves all are keys for a mate in 7:
5. d3, 5. b3 and 5. Nc3.

Quite an interesting problem :-)
But since both those mate in 7 did eat up more than an hour of CPU time,
the original problem is still too large for my program.  :-(

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