Author: Dieter Buerssner
Date: 02:37:35 08/11/02
Go up one level in this thread
On August 10, 2002 at 21:53:49, John Merlino wrote:
>Here is a position from a game that Slater and I discussed in a different
>thread:
>
>[D]3R4/8/8/8/2K5/6p1/3p1rk1/8 b - - 0 78
>
>In that game, Black was obviously using EGTBs and played 78...d1=Q, leading to
>an EGTB mate in 22 moves (including the promotion). However, the more natural
>looking move, Kf1, leads to a mate in 14, as Chessmaster 9000 shows on a
>PIII-733:
>
>Time Depth Score Positions Moves
[... 9
>3:06 8/12 -15.25 19391217 78...Kf1 79.Kc3 Ke1 80.Kc4 g2 81.Re8+
> Kf1 82.Rd8 g1=Q 83.Rd4 Qg8+ 84.Kc5
> Qg5+ 85.Kc4 Rf4 86.Kb3 Rxd4
>9:45 9/13 -Mate14 62576834 78...Kf1 79.Kc3 Ke1 80.Kc4 g2 81.Re8+
> Re2 82.Rd8 g1=Q 83.Rd6 Qg8+ 84.Kb4
> Qb8+ 85.Kc4 Qc7+ 86.Kb5 Re5+ 87.Kb4
> Qc5+ 88.Kb3 Re3+ 89.Rd3 Rxd3+ 90.Kb2
> Qc1+ 91.Ka2 Ra3#
>
>Note that the first capture is 23 ply away, making it very difficult
>(impossible?) to find it via tablebases. Can anybody else find the mate faster?
It took a long time, but Yace with TBs can find a mate in 11. Only a small set
of 5-men TBs was used, but they included KRPKR - tho only one really useful
here?
108261 1.537 29.14 8. 78...d1=Q 79. Rd2 Qxd2 80. Kc5 Qd6+ 81. Kc4
Qd5+ 82. Kb4 {1581}
110884 1.579 Mat26 9++ 78...d1=Q 79. Kb4 Rb2+ 80. Kc5H Qd4+H 81. Kc6H
Qd6+H 82. Rxd6H {EGTB} 82...Rf2 83. Re6 Rf5 84.
Rd6! Rh5 85. Rd2+! Kg1 86. Rd3 g2 87. Rd1+!
Kh2! 88. Rd2! Kh1! 89. Rd1+! {Not all positions
found in TB} {80}
173008 2.151 Mat22 9t 78...d1=Q 79. Rxd1 {EGTB} 79...Rf4+ 80. Kc5
Kh2! 81. Kd5 Rh4 82. Rd2+ g2! 83. Rc2 Kh1! 84.
Rc1+! {Not all positions found in TB} {80}
[...]
2069327 19.231 Mat21 12t+ 78...Rf8 79. Rxd2+ {EGTB} 79...Kg1 80. Re2 Rh8
81. Re3 g2 82. Rf3 Rh5 83. Rf6 Kh1 84. Rg6!
{Not all positions found in TB} {80}
2069347 19.417 Mat21 12t 78...Rf8 79. Rxd2+ {EGTB} 79...Kg1 80. Re2 Rh8
81. Re3 g2 82. Rf3 Rh5 83. Rf6 Kh1 84. Rg6!
{Not all positions found in TB} {80}
[...]
228529819 39:15.9 Mat20 16t+ 78...Rf4+ 79. Kc5 Kh3 80. Kc6 g2 81. Rh8+ Kg4
82. Kc7 g1=Q {HT} {1081}
446295442 1:09:03 Mat19 16t 78...Rf4+ 79. Kc5 Kh3 80. Rd3 Rf1 81. Rxd2
{EGTB} 81...g2! 82. Rxg2! Kxg2! 83. Kd5 Rd1+
84. Kc5 Kg3 85. Kc6 Kf3 86. Kc7 Rd5 87. Kc8 Kf4
88. Kb8 Rd6 89. Kc8 Kf5 90. Kb8 Rd7 91. Kc8 Re7
92. Kd8 Ke6! 93. Kc8 Kd6! 94. Kd8 Re5 95. Kc8
Rb5! 96. Kd8 Rb8#! {500}
503252253 1:17:26 Mat18 16t+ 78...Kf3 79. Rf8+ Ke2 80. Re8+ Kf1 81. Rd8 g2
82. Kc3 Rf4 83. Re8 g1=Q 84. Kxd2 Qd4+ 85. Kc2
Rf2+ 86. Re2 Qb2+ 87. Kxb2 {EGTB} 87...Kxe2!
88. Kb3! Rf4 89. Kc3! Rg4 90. Kc2 Rg3! 91. Kc1
Kd3! 92. Kb2! Kd2! 93. Kb1 Kc3! 94. Ka1 Kb3!
95. Kb1 Rg1#! {500}
671270403 1:41:04 Mat13 16t 78...Kf3 79. Rf8+ Ke2 80. Re8+ Kf1 81. Rd8 g2
82. Kb5 g1=Q 83. Rd5 d1=RH {HT} {1501}
677917230 1:42:00 Mat13 16. 78...Kf3 79. Rf8+ Ke2 80. Re8+ Kf1 81. Rd8 g2
82. Kb5 g1=Q 83. Rd5 d1=R {HT} {1501}
1129147563 2:37:19 Mat12 17t 78...Kf3 79. Rf8+ Ke2 80. Re8+ Kf1 81. Rd8 g2
82. Kb5 g1=Q 83. Rd4 Rf5+ 84. Kc4 Qxd4+ 85.
Kxd4 {EGTB} 85...d1=Q+ 86. Kc4 Qd2 87. Kb3
Qd3+! 88. Kb4 Rb5+! 89. Ka4 Qb3#! {1501}
1161015095 2:41:19 Mat11 17t+ 78...Kf1 79. Kc5 g2 80. Rd6 g1=Q 81. Kc6 Rf5
82. Rxd2 Qc5+ 83. Kb7 Rf7+ 84. Ka6 Qc6+ 85. Ka5
Ra7+ 86. Kb4 Rb7+ 87. Ka5 Qb6+ 88. Ka4 {HT}
{1001}
1249329646 2:49:57 Mat11 17t 78...Kf1 79. Kc3 g2 80. Rxd2 {EGTB} 80...Rxd2
81. Kxd2! g1=Q! 82. Kc3! Qg4 83. Kd3 Qh4 84.
Ke3 Qc4 85. Kf3! Qd4! 86. Kg3 Qe4! 87. Kh3!
Kf2! 88. Kh2 Qh4# {1001}
1266236230 2:51:50 Mat11 17. 78...Kf1 79. Kc3 g2 80. Rxd2 {EGTB} 80...Rxd2!
81. Kxd2! g1=Q! 82. Kc3! Qg4 83. Kd3 Qh4 84.
Ke3 Qc4 85. Kf3! Qd4! 86. Kg3 Qe4! 87. Kh3!
Kf2! 88. Kh2 Qh4# {1001}
The last line only has one check - the checkmate. So, I guess also without TBs
it would be very difficult to find. Other than this, I agree, that sometimes
(but only when the position is an easy win already?) TBs will make the engine to
go for a longer mate. But don't humans do this, too? Say I have a KRPKP - I
perhaps in some positions would just sac the R against opponent P, when my P
easily promotes, without thinking hard about promoting the P first and win
faster. Just because I know, how easily even I can win the following ending.
Engines with TBs do similar - only that they know how to win many more endings
than me very easily with TB support. But there are also some very small pitfalls
- say a mate in 80 from KBBKN TB, that actually is a draw according to chess
rules, due to the 50 moves rule.
Regards,
Dieter
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