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Subject: Re: Endgame Suite

Author: Howard Exner

Date: 20:58:55 01/18/98

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On January 18, 1998 at 12:31:40, Ernst A. Heinz wrote:

>Dear Howard,
>
>Thank you very much for the nice endgame suite.
>
>Below follow the results of "DarkThought" on our 500MHz DEC Alpha-21164a
>PC164 (all 4-piece endgame tablebases enabled, time to *stable*
>solution):
>
> 1.   0 sec  (mate in 19 after 4 sec)
Do you have knowledge for this one and #9 or are they both
tablebase solutions?

> 2.   0 sec
> 3.   -?-    (prefers Kd5 after 0 sec, score = +1.27)

The point of this problem is to avoid Kc3? as Kxg6 draws.After
Kd5 you will have to follow up on how to reply to Ra5+. Kc4 in reply
to Ra5+ will again draw but Kc6 will be correct. The king has to
stay close to the white queening square after the exchange on a1.

> 4.  19 sec
> 5.   0 sec
> 6.   0 sec
> 7.   0 sec
> 8. [ 0 sec] (prefers Kg3 announcing a mate in 17 ==> Qxh7 not unique!)

#9 and #1 are basic drawing positions to be on the alert for.

> 9.   -?-    (prefers a2 after 0 sec, score = +2.43)

This one may be too deep. After a2 I see no win as black is unable
to avoid the Rook checks on the king. A little knowledge would go
a long way in solving this one. Does anyone see a win for black after
a2?

>10.   0 sec
>11.   0 sec
>12.   -?-    (changes between Bxc5 and Be3, prefers Bxc5 in the end)

Bx5 definitely loses here to 1. ... Kxc5 2. Kd3 Kb4 3.Kc2 Ka3 4.Kb1 a5
5.Ka1 a4 6.bxa4 Kxa4! 7.Kb2 b4 and so on. After Black forces the
exchange
of the b and a pawns the kingside pawns will fall.This probably falls
into
the category, easy for humans but hard for machines.

>13.   0 sec
>14.  82 sec
>15.   6 sec
>16.   0 sec
>17.   0 sec
>18. 378 sec
>19.  44 sec
>20.  35 sec
>21.  76 sec
>22.   ---

#22 shows how difficult the Louguet-2 End#9 really is. I wonder
which programs that were given credit for solving Louguet-2 would
find this?



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