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Old March 8th 07, 02:45 PM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines

Please can anyone recommend a chess engine that excels at analysing
endgames (with or without tablebases).

There are a whole bunch of positions that arise in games that are far
enough from the table base horizon but still relatively simple where
their brute force analysis is too time consuming. The sort of position
I have in mind is something like:

8/8/8/8/R1b3p1/3kp1P1/7P/4K3 w - - 0 72

that arose in a game I had recently. Although I still think it is
drawn with best play the material imbalance makes Shredder 10 (and
other engines) think that white is ahead and even at ply 26 after a
few hours it can't do any better than not losing the rook. No signs of
a win in prospect...

Roughly I think that almost any move that doesn't lose the rook leads
to a draw with best play.

Even the dodgy h3, h4 losing a pawn seems to lead to a neutral
material drawn position. And the very dodgy Kf1 allowing the
discovered check also seems to lead to a drawn position with material
balance reversed. (I am less sure of this)

Rxc4 clearly loses, as does putting the rook en prise.

Endgames are not my strong point so I'd be grateful for any advice or
corrections - and particularly for suggestions of which engine(s) are
most likely to give informative endgame analysis reasonably quickly
(eg 2-3 hours).

Regards,
Martin Brown

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Old March 8th 07, 03:18 PM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines

Martin Brown wrote:
Please can anyone recommend a chess engine that excels at analysing
endgames (with or without tablebases).


Freezer? I've never tried it but it sounds like just the thing you're
looking for. The idea is that you can tell it things like ``White
loses if he loses the rook or moves his king outside the square
a1-a4-d1-d4.'' It will then analyze the position taking into account
your instructions.

http://www.freezerchess.com/

(Standard disclaimer: I have no association with this software, etc.)


Dave.

--
David Richerby Generic Soap (TM): it's like a
www.chiark.greenend.org.uk/~davidr/ personal hygiene product but it's just
like all the others!
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Old March 8th 07, 03:28 PM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines


"Martin Brown" schreef in bericht
oups.com...
Please can anyone recommend a chess engine that excels at analysing
endgames (with or without tablebases).

There are a whole bunch of positions that arise in games that are far
enough from the table base horizon but still relatively simple where
their brute force analysis is too time consuming. The sort of position
I have in mind is something like:

8/8/8/8/R1b3p1/3kp1P1/7P/4K3 w - - 0 72

that arose in a game I had recently. Although I still think it is
drawn with best play the material imbalance makes Shredder 10 (and
other engines) think that white is ahead and even at ply 26 after a
few hours it can't do any better than not losing the rook. No signs of
a win in prospect...

Roughly I think that almost any move that doesn't lose the rook leads
to a draw with best play.

Even the dodgy h3, h4 losing a pawn seems to lead to a neutral
material drawn position. And the very dodgy Kf1 allowing the
discovered check also seems to lead to a drawn position with material
balance reversed. (I am less sure of this)

Rxc4 clearly loses, as does putting the rook en prise.

Endgames are not my strong point so I'd be grateful for any advice or
corrections - and particularly for suggestions of which engine(s) are
most likely to give informative endgame analysis reasonably quickly
(eg 2-3 hours).

Regards,
Martin Brown



Fruit and Rybka seem to manage a win for white.
With his rook it looks like white can split up the K and B, and he can
either win the e- or the g-pawn. If white takes the g-pawn, it's obviously
easy to see he will win.
The e-pawn needs some more moves, but I think, that white could get his K
and R near the g-pawn, and exchange the rook for the B+pawn, and winning a
2-pawn advantage.
Fruit 2.2.1: 1.Ta4-a3+ Kd3-d4 2.Ta3-a7 Kd4-e4 3.Ta7-c7 Ke4-d3 4.Tc7-d7+
Kd3-e4 5.Td7-b7 e3-e2 6.Tb7-c7 Lc4-a6 7.Tc7-e7+ Ke4-f3 8.Te7-a7 La6-b5
9.Ta7-b7 Lb5-d3 10.Tb7-b4 Ld3-c2 11.Tb4-f4+ Kf3-e3 12.Tf4xg4 Lc2-d3 13.h2-h4
Ke3-f3 14.Tg4-d4 Ld3-g6 15.g3-g4 Lg6-c2 16.h4-h5 2.62/26 ;
Rybka 1.2f 32-bit: 1.Ta4-a8 Kd3-e4 2.Ta8-c8 Lc4-b3 3.Ke1-e2 Ke4-d4 4.Tc8-d8+
Lb3-d5 5.Td8-d7 Kd4-e4 6.Td7-e7+ Ke4-d4 7.Te7xe3 Ld5-f7 2.58/22

I'm sure it will take a master level of explaining on how to do the
splitting-up, but I would give it a serious try if I had white in this
position.


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Old March 8th 07, 04:41 PM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines

Hi,

YACE is one of the best when it comes to endgame analysis. There are also
some articles about its achievements but they are in German.
http://www.lbremer.de/artikel/Yace.pdf
http://www.lbremer.de/artikel/tabldisk.pdf
http://www.chesscoach.de/yace.html

The engine itself can be downloaded he

http://home1.stofanet.dk/moq/


For the program Freezer you need to put your own knowledge inside. Doing so
you can achieve impressive reults in some cases but not always. Here is an
interview with the author of Freezer:

http://exactachess.com/modules.php?n...erviews&page=6


Best,
Michael


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Old March 9th 07, 08:58 AM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines

On Mar 8, 3:28 pm, "Ruud" wrote:
"Martin Brown" schreef in ooglegroups.com...

Please can anyone recommend a chess engine that excels at analysing
endgames (with or without tablebases).


I have in mind is something like:


8/8/8/8/R1b3p1/3kp1P1/7P/4K3 w - - 0 72


Roughly I think that almost any move that doesn't lose the rook leads
to a draw with best play.


Even the dodgy h3, h4 losing a pawn seems to lead to a neutral
material drawn position. And the very dodgy Kf1 allowing the
discovered check also seems to lead to a drawn position with material
balance reversed. (I am less sure of this)


Rxc4 clearly loses, as does putting the rook en prise.


Interesting but annoying point here - in infinite analysis at ply
search depths (currently 28) way beyond what is needed to resolve the
problem after losing the rook as a mate in 11,10,9,9 respectively. The
software knows the forced winning principle variation to update the
status screen so why can it not skip these lines that are fully
resolved?
(I have it set to show all the moves at present)

This only ever seems to happen with forced mating sequences wasting
hours of CPU time. Moves that lose huge amounts of material are very
quickly dealt with in deep infinite analysis.

Endgames are not my strong point so I'd be grateful for any advice or
corrections - and particularly for suggestions of which engine(s) are
most likely to give informative endgame analysis reasonably quickly
(eg 2-3 hours).


Fruit and Rybka seem to manage a win for white.
With his rook it looks like white can split up the K and B, and he can
either win the e- or the g-pawn. If white takes the g-pawn, it's obviously
easy to see he will win.


Agreed. What I can't find is a way to execute that plan!

The e-pawn needs some more moves, but I think, that white could get his K
and R near the g-pawn, and exchange the rook for the B+pawn, and winning a
2-pawn advantage.
Fruit 2.2.1: 1.Ta4-a3+ Kd3-d4 2.Ta3-a7 Kd4-e4 3.Ta7-c7 Ke4-d3 4.Tc7-d7+
Kd3-e4 5.Td7-b7 e3-e2 6.Tb7-c7 Lc4-a6 7.Tc7-e7+ Ke4-f3 8.Te7-a7 La6-b5
9.Ta7-b7 Lb5-d3 10.Tb7-b4 Ld3-c2 11.Tb4-f4+ Kf3-e3 12.Tf4xg4 Lc2-d3 13.h2-h4
Ke3-f3 14.Tg4-d4 Ld3-g6 15.g3-g4 Lg6-c2 16.h4-h5 2.62/26 ;


Thanks for these Ruud. BTW How did you get it to show the principle
variation out so far?
I suspect that 1. ... Kd4 is weaker for black than Ke4 in this
variation but that it is advancing 5. ... e2 losing K shelter and
without the prospect of promotion that effectively loses the g-pawn.
My instinct is that 5. ... Kf3 holds the draw.
(but I am not very good at endgames)

Rybka 1.2f 32-bit: 1.Ta4-a8 Kd3-e4 2.Ta8-c8 Lc4-b3 3.Ke1-e2 Ke4-d4 4.Tc8-d8+
Lb3-d5 5.Td8-d7 Kd4-e4 6.Td7-e7+ Ke4-d4 7.Te7xe3 Ld5-f7 2.58/22


Shredder thinks 2. Rf8 is better and refuses to play along with 2. ...
Bb3

I'm sure it will take a master level of explaining on how to do the
splitting-up, but I would give it a serious try if I had white in this
position.- Hide quoted text -


But against a stronger player I was happy to take a draw. I was a
little bit annoyed to find that earlier in the game I had missed a win
at move 30 when I chose to snatch the rook instead of entering a
materially equal but positionally superior endgame. And I thought at
the time I was avoiding a difficult endgame...

These are the main Shredder analysis lines at ply 27 for comparison:

3.33/27
1. Ra7 Bd5 2. Ra3+ Kd4 3. Ra4+ Bc4 4. Ra7
1. Ra3 Kc4 2. Rf8 Kd3 3. Rf5 Be6 4. Rb5 Kd4 5. Rb7 Kd3 6. Rg7
1. Rb4 e2 2. Ra4 Kd4 3. Kd2 Kd5 4. Ra8 Ke4 5. Rf8 e1Q+

2.96/27
1. Ra3+ Ke4 2. Ra8 Kf3 3. Ra4 Be6 4. Kf1 e2+ 5. Ke1 Bd7 6. Rb4 Be6
1. Ra5 Ke4 2. (ditto)
1. Ra1 Ke4 2. Ra7 (ditto)

0.01/27
1.h3 gxh3 2. Ra8 Be6 3. Rd8+ Ke4 4. Re8 Kf5 5. Ke1 h2 6. Rh8 Kg4 7.
Rxh2 Kxg3
1. h4 (ditto)

-3.90/27
1. Kf1? Kd2+ 2. Rxc4 e2+ 3. Kg2 e1Q 4. Rd4+ Kc1 5. Rc4+ Kd1 6. Rd4+
Kc2

The rest are obviously lost 1. Rxc4 #11/27, 1. Kd1 #10/27, 1. Ra2
#9/27, 1. Ra6 #9/27

(and that is all the poxy status window will show me of the principle
variations)

Regards,
Martin Brown



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Old March 9th 07, 01:52 PM posted to rec.games.chess.computer,rec.games.chess.analysis
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Default Endgames & Engines


"Martin Brown" schreef in bericht
ups.com...
On Mar 8, 3:28 pm, "Ruud" wrote:
"Martin Brown" schreef in
ooglegroups.com...

Please can anyone recommend a chess engine that excels at analysing
endgames (with or without tablebases).


I have in mind is something like:


8/8/8/8/R1b3p1/3kp1P1/7P/4K3 w - - 0 72


Roughly I think that almost any move that doesn't lose the rook leads
to a draw with best play.


Even the dodgy h3, h4 losing a pawn seems to lead to a neutral
material drawn position. And the very dodgy Kf1 allowing the
discovered check also seems to lead to a drawn position with material
balance reversed. (I am less sure of this)


Rxc4 clearly loses, as does putting the rook en prise.


Interesting but annoying point here - in infinite analysis at ply
search depths (currently 28) way beyond what is needed to resolve the
problem after losing the rook as a mate in 11,10,9,9 respectively. The
software knows the forced winning principle variation to update the
status screen so why can it not skip these lines that are fully
resolved?
(I have it set to show all the moves at present)

This only ever seems to happen with forced mating sequences wasting
hours of CPU time. Moves that lose huge amounts of material are very
quickly dealt with in deep infinite analysis.

Endgames are not my strong point so I'd be grateful for any advice or
corrections - and particularly for suggestions of which engine(s) are
most likely to give informative endgame analysis reasonably quickly
(eg 2-3 hours).


Fruit and Rybka seem to manage a win for white.
With his rook it looks like white can split up the K and B, and he can
either win the e- or the g-pawn. If white takes the g-pawn, it's
obviously
easy to see he will win.


Agreed. What I can't find is a way to execute that plan!


As I said, I'm no Master level player.
The manouvre of the rook vs the K+B combo, with the threat of moving the
white K to the e-pawn, is however an edge, wich is clear to see. It could be
enough to try and play on.


The e-pawn needs some more moves, but I think, that white could get his K
and R near the g-pawn, and exchange the rook for the B+pawn, and winning
a
2-pawn advantage.
Fruit 2.2.1: 1.Ta4-a3+ Kd3-d4 2.Ta3-a7 Kd4-e4 3.Ta7-c7 Ke4-d3 4.Tc7-d7+
Kd3-e4 5.Td7-b7 e3-e2 6.Tb7-c7 Lc4-a6 7.Tc7-e7+ Ke4-f3 8.Te7-a7 La6-b5
9.Ta7-b7 Lb5-d3 10.Tb7-b4 Ld3-c2 11.Tb4-f4+ Kf3-e3 12.Tf4xg4 Lc2-d3
13.h2-h4
Ke3-f3 14.Tg4-d4 Ld3-g6 15.g3-g4 Lg6-c2 16.h4-h5 2.62/26 ;


Thanks for these Ruud. BTW How did you get it to show the principle
variation out so far?


I just copied the analysis to the notation, in my Junior (like Shredder in
chessbase).
I'm really not convinced that it has the best replies to moves from both
sides.
For instance, after the moves

1.Ta4-b4 Kd3-d4 2.Tb4-b6 Lc4-d5 3.Tb6-g6 Ld5-f3 4.Tg6-f6
FEN:
8/8/5R2/8/3k2p1/4pbP1/7P/4K3 b - - 0 4

It looks like black is ok. The white K can't get to the e pawn, and black K
can defend the e pawn against the rook.
However: the threat of h2-h4 is evident. Which proves that black can't 'lock
up' the game like this, and has to move the B again. After which white's K
can perhaps move up the board.

Untill so far,
Regards from Ruud.


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