## Simple mate in 6 that gives some engines trouble

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mwyoung
Posts: 2331
Joined: Wed May 12, 2010 8:00 pm

### Re: Simple mate in 6 that gives some engines trouble

Dann Corbit wrote:
Thu May 02, 2019 12:34 am
acn 883293; acs 2; bm Nh6; ce 32756; dm 6; pv Nh6 gxh6 Re5 dxe5 Qf6+ exf6 Ne3 dxe3 Rf5 g1=Q Rh5#;
No issues with Lc0.

New game Line
b4bN1/4p1p1/1Q1p2K1/q1np4/3p1Rnk/6pr/4Rppr/3N4 w - - 0 1

Analysis by Lc0 v0.21.1:

1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
White is clearly winning: +- (5.83) Depth: 10/30 00:00:21 535kN
(, 02.05.2019)
Professing themselves to be wise, they became fools,
take on me. Foes 0.

zullil
Posts: 6442
Joined: Mon Jan 08, 2007 11:31 pm
Location: PA USA
Full name: Louis Zulli

### Re: Simple mate in 6 that gives some engines trouble

Cute theme, in any case. Black pawns are forced onto certain squares, so that---even after the pin is removed---the knight on g4 has no moves.

lech
Posts: 1082
Joined: Sun Feb 14, 2010 9:02 pm

### Re: Simple mate in 6 that gives some engines trouble

Dann Corbit wrote:
Thu May 02, 2019 4:57 am
I think the problem is null move pruning found in the strongest engines.
If you look at the pv, they give up 3 pieces in succession, including the queen!
Now, it is just a 12 ply combination. So it ought to be real simple.
But heavy pruning can push it way off into the distance.
But after each of the white moves (sacrifices) there is a threat or check and the null move pruning is not the reason. Try again!
Maybe, I can't be friendly, but let me be useful.

acase
Posts: 734
Joined: Wed Mar 15, 2006 12:14 am
Location: Columbus, Ohio USA
Full name: Andrew R Case

### Re: Simple mate in 6 that gives some engines trouble

Rofchade 2.1 gets this one and Houdini 4 seems pretty fast, but the Rofchade analysis looks pretty wild, teetering back and forth between (#6) and (-#1989)

Code: Select all

``````New game
b4bN1/4p1p1/1Q1p2K1/q1np4/3p1Rnk/6pr/4Rppr/3N4 w - - 0 1

1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-17.12)  Depth: 13/26   00:00:00  625kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-18.76)  Depth: 14/26   00:00:00  1268kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-19.12)  Depth: 15/28   00:00:00  1960kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-18.76)  Depth: 16/31   00:00:00  3034kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-19.80)  Depth: 17/31   00:00:01  5926kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1
-+ (-21.02)  Depth: 18/37   00:00:02  17844kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-21.48)  Depth: 19/37   00:00:03  28691kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-21.75)  Depth: 20/38   00:00:04  37570kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-22.50)  Depth: 21/38   00:00:06  61871kN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-23.71)  Depth: 22/38   00:00:13  134MN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-24.02)  Depth: 23/40   00:00:20  201MN
1.Qxa5 f1Q 2.Qd2 g1Q 3.Rxf1 Ne4 4.Rxe4
-+ (-25.01)  Depth: 24/50   00:00:36  363MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 25/50   00:01:28  894MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 25/50   00:01:28  894MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 26/50   00:01:28  898MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 26/50   00:01:28  898MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 27/50   00:01:29  909MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 27/50   00:01:29  909MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 28/50   00:01:30  923MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 28/50   00:01:30  923MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 29/50   00:01:33  957MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 29/50   00:01:33  957MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 30/50   00:01:34  962MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 30/50   00:01:34  962MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 31/50   00:01:34  971MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 31/50   00:01:34  971MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 32/50   00:01:37  1000MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 32/50   00:01:37  1000MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 33/50   00:01:39  1024MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 33/50   00:01:39  1024MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 34/50   00:01:43  1072MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 34/50   00:01:43  1072MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 35/50   00:01:46  1109MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 35/50   00:01:46  1109MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 36/50   00:01:49  1153MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 36/50   00:01:49  1153MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 37/50   00:01:55  1235MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 37/50   00:01:55  1235MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 38/50   00:02:00  1295MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 38/50   00:02:00  1295MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 39/50   00:02:17  1514MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 39/50   00:02:17  1514MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 40/50   00:02:20  1559MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 40/50   00:02:20  1559MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 41/50   00:02:37  1766MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 41/50   00:02:37  1766MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 42/50   00:02:42  1847MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 42/50   00:02:42  1847MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 43/50   00:02:47  1906MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 43/50   00:02:47  1906MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 44/50   00:03:23  2381MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 44/50   00:03:23  2381MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
-+ (-#1989)  Depth: 45/50   00:05:02  3528MN
1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
+- (#6)  Depth: 45/50   00:05:02  3528MN

``````

chrisw
Posts: 3629
Joined: Tue Apr 03, 2012 2:28 pm

### Re: Simple mate in 6 that gives some engines trouble

Dann Corbit wrote:
Thu May 02, 2019 12:34 am
acn 883293; acs 2; bm Nh6; ce 32756; dm 6; pv Nh6 gxh6 Re5 dxe5 Qf6+ exf6 Ne3 dxe3 Rf5 g1=Q Rh5#;
The set of positions that require a specific sequence of materially losing moves of the type current strong AB engines will prune away (a main reason for their strength), followed by a sudden tactical mate probably approaches infinity. But this nearly infinite set occurs in actual real chess games at an infinitesimally small rate.

Ronald
Posts: 108
Joined: Tue Jan 23, 2018 9:18 am
Location: Rotterdam
Full name: Ronald Friederich
Contact:

### Re: Simple mate in 6 that gives some engines trouble

acase wrote:
Sat May 04, 2019 9:10 am
Rofchade 2.1 gets this one and Houdini 4 seems pretty fast, but the Rofchade analysis looks pretty wild, teetering back and forth between (#6) and (-#1989)

I think what happens is that rofChade first generates a generic info score string with the score 31989, which means a mate in 11 ply. Because the mate is "proven" (the searchdepth is equal or greater than the matedepth) it generates an extra "info mate" string to announce the mate.

Code: Select all

``````info score cp 31989 depth 26 seldepth 48 nodes 2133093857 nps 9797418 time 217720 tbhits 0 pv g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 c5e6 f5h5
info score mate 6 depth 26 nodes 2133094216 nps 9797419 time 217720 tbhits 0 pv g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 c5e6 f5h5 ``````

acase
Posts: 734
Joined: Wed Mar 15, 2006 12:14 am
Location: Columbus, Ohio USA
Full name: Andrew R Case

### Re: Simple mate in 6 that gives some engines trouble

Ronald wrote:
Sat May 04, 2019 11:12 am
acase wrote:
Sat May 04, 2019 9:10 am
Rofchade 2.1 gets this one and Houdini 4 seems pretty fast, but the Rofchade analysis looks pretty wild, teetering back and forth between (#6) and (-#1989)

I think what happens is that rofChade first generates a generic info score string with the score 31989, which means a mate in 11 ply. Because the mate is "proven" (the searchdepth is equal or greater than the matedepth) it generates an extra "info mate" string to announce the mate.

Code: Select all

``````info score cp 31989 depth 26 seldepth 48 nodes 2133093857 nps 9797418 time 217720 tbhits 0 pv g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 c5e6 f5h5
info score mate 6 depth 26 nodes 2133094216 nps 9797419 time 217720 tbhits 0 pv g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 c5e6 f5h5 ``````

Hi Ronald, thanks for your fine engine, and my apologies for spelling rofChade incorrectly.

MikeB
Posts: 4355
Joined: Thu Mar 09, 2006 5:34 am
Location: Pen Argyl, Pennsylvania

### Re: Simple mate in 6 that gives some engines trouble

mwyoung wrote:
Thu May 02, 2019 6:53 pm
Dann Corbit wrote:
Thu May 02, 2019 12:34 am
acn 883293; acs 2; bm Nh6; ce 32756; dm 6; pv Nh6 gxh6 Re5 dxe5 Qf6+ exf6 Ne3 dxe3 Rf5 g1=Q Rh5#;
No issues with Lc0.

New game Line
b4bN1/4p1p1/1Q1p2K1/q1np4/3p1Rnk/6pr/4Rppr/3N4 w - - 0 1

Analysis by Lc0 v0.21.1:

1.Nh6 gxh6 2.Re5 dxe5 3.Qf6+ exf6 4.Ne3 dxe3 5.Rf5 f1Q 6.Rh5#
White is clearly winning: +- (5.83) Depth: 10/30 00:00:21 535kN
(, 02.05.2019)
You think it's not going to find it and then bada boom bada bing, it finds it:

Code: Select all

`````` 32	    #6 	2.77G	1:34.32	Nh6 gxh6 Re5 dxe5 Qf6+ exf6 Ne3 dxe3 Rf5 Qa6 Rh5#
31	    #6 	2.77G	1:34.32	Nh6 gxh6 Re5 dxe5 Qf6+ exf6 Ne3 dxe3 Rf5 Qa6 Rh5#
30	    #6!	2.77G	1:34.32	Nh6!
30	 -21.66?	1.94G	1:07.70	Qxa5 Bc6?
30	 -20.31?	1.45G	0:50.29	Qxa5 Bc6?
29	 -18.97 	1.26G	0:43.94	Qxa5 Bc6 Rxf8 Nd7 Qd8 Nxf8+ Qxf8 f1=Q Qxe7+ Nf6 Re6 Qf4 Nxf6 Qg5+ Kf7 g1=Q Ne8 Qxe7+ Kxe7 Qxd1 Nxg7 g2 Rh6+ Kg5 Rxh3 g1=Q
29	 -18.90!	1.26G	0:43.80	Qxa5!
29	 -19.50!	1.26G	0:43.79	Qxa5!
29	 -19.97!	1.26G	0:43.79	Qxa5!
29	 -20.33!	1.26G	0:43.78	Qxa5!
29	 -20.61!	1.26G	0:43.78	Qxa5!
29	 -20.82!	1.26G	0:43.78	Qxa5!
29	 -20.98!	1.26G	0:43.78	Qxa5!
29	 -21.09!	1.26G	0:43.78	Qxa5!
29	 -21.17!	1.26G	0:43.78	Qxa5!
29	 -21.22!	1.26G	0:43.77	Qxa5!
28	 -21.27 	1.23G	0:42.61	Qxa5 Bc6 Nh6 gxh6 Rexf2 g1=Q Rf1 Qg2 Kf7 Rh1 R1f3 Rxd1 Qa3 e5 Rf5 e4 R3f4 Qd2 Kxf8 Ne6+ Kg8 Nxf4 Qxd6 g2 Rxf4 g1=Q Qe7+ Kg3 Rf5 Qc1 Kh7 Kg2 Qf7 Rg3 Rh5 Qf1 Qxf1+ Rxf1 Kg7 Ne5+ Kh7 Rf7+ Kh8
28	 -20.70?	998.6M	0:34.66	Qxa5 Bc6?
28	 -19.28!	639.3M	0:22.10	Qxa5!
27	 -19.33 	570.3M	0:19.69	Qxa5 Bc6 Nh6 gxh6 Nxf2 gxf2 Rexf2 g1=Q Rf1 Qe3 Qe1+ Qxe1 Rxe1 Nd3 Rxf8 Nxe1 Rb8 Ne5+ Kg7 d3 Rb4+ Kg5 Rb8 Kg4 Rb1 d2 Rb4+ Kg3 Rb1 Kh4 Ra1
27	 -16.88!	566.2M	0:19.54	Qxa5!
27	 -17.47!	566.2M	0:19.54	Qxa5!
27	 -17.94!	566.2M	0:19.54	Qxa5!
27	 -18.30!	565.6M	0:19.52	Qxa5!
27	 -18.57!	554.8M	0:19.13	Qxa5!
27	 -18.78!	554.6M	0:19.12	Qxa5!
27	 -18.94!	554.3M	0:19.11	Qxa5!
27	 -19.05!	553.6M	0:19.08	Qxa5!
27	 -19.13!	546.7M	0:18.84	Qxa5!
27	 -19.18!	543.8M	0:18.73	Qxa5!
26	 -19.23 	537.0M	0:18.50	Qxa5 Bc6 Nh6 gxh6 Rexf2 g1=Q Rf1 Qg2 Re1 Be8+ Kh7 Nd7 Kh8 Nf6 Re6 Qc2 Rxg4+ Kxg4 Rxf6 exf6 Qxd5 g2 Qe6+ Kg3 Qe1+ Kf3 Qxe8 g1=Q Qxf8 Qcg6 Qa8+ Kg4 Qa1 Qg5 Qa8
26	 -17.79?	363.2M	0:12.53	Qxa5 Bc6?
26	 -16.49?	292.8M	0:10.12	Qxa5 Bc6?
26	 -15.46?	254.7M	0:08.81	Qxa5 Bc6?
25	 -14.43 	232.9M	0:08.05	Qxa5 Bc6 Rxf8 Nd7 Qd8 Nxf8+ Qxf8 f1=Q Qxe7+ Nf6 Kxg7 g1=Q Re6 Qxd1 Qxf6+ Kg4 Qg6+ Kh4
25	 -11.49!	232.9M	0:08.05	Qxa5!
25	 -12.71!	232.7M	0:08.04	Qxa5!
25	 -13.67!	232.6M	0:08.04	Qxa5!
25	 -14.44!	232.5M	0:08.04	Qxa5!
25	 -15.04!	232.5M	0:08.04	Qxa5!
25	 -15.50!	232.5M	0:08.04	Qxa5!
25	 -15.87!	232.4M	0:08.03	Qxa5!
25	 -16.15!	232.4M	0:08.03	Qxa5!
25	 -16.40!	232.3M	0:08.03	Qxa5!
25	 -16.56!	232.3M	0:08.03	Qxa5!
25	 -16.67!	232.2M	0:08.03	Qxa5!
25	 -16.75!	231.3M	0:08.00	Qxa5!
25	 -17.35?	230.9M	0:07.98	Qxa5 Bc6?
24	 -16.20 	204.5M	0:07.05	Qxa5 Bc6 Rxf8 Nd7 Rf4 f1=Q Nxe7 Qxf4 Nf5+ Qxf5+ Kxf5 g1=Q Re1 Rf2+ Ke6 Rf6+ Ke7 Rf1 Kxd6 Rxe1 Qd8+ Ndf6 Kxc6 Rxd1 Qh8+ Nh5 Qd8+ Ngf6
24	 -15.96!	204.4M	0:07.05	Qxa5!
24	 -16.34!	204.4M	0:07.05	Qxa5!
24	 -16.65!	204.4M	0:07.05	Qxa5!
24	 -16.87!	204.3M	0:07.05	Qxa5!
24	 -17.03!	204.3M	0:07.04	Qxa5!
24	 -17.17!	204.3M	0:07.04	Qxa5!
24	 -17.25!	204.2M	0:07.04	Qxa5!
24	 -17.30!	199.1M	0:06.86	Qxa5!
23	 -17.35 	178.3M	0:06.14	Qxa5 Bc6 Nh6 gxh6 Rexf2 g1=Q Rf1 Qg2 Rxf8 Qc2+ Kg7 Ne6+ Kh8 Nxf8 Rxf8 Qxd1 Qd8 Re2 Rf7 g2 Rxe7 g1=Q Rxe2+ Kh5 Re7 Rf3 Rc7 Ne5 Qxd6 Rf8+ Qxf8 Ng6+ Kg8 Nxf8+ Kxf8
23	 -16.35!	109.7M	0:03.77	Qxa5!
22	 -16.40 	99.1M  	0:03.41	Qxa5 Bc6 Rxf8 Nd7 Qd8 Nxf8+ Qxf8 f1=Q Qxe7+ Nf6 Kxg7 g1=Q Re6 Qf5 Rxf6 Qe5 Qxe5 dxe5 Rh6+ Kg4 Rxc6 Qxd1 Rg6+ Kf4 Kf8 g2 Rxg2 Rxg2 Nf6 Rh6 Nd7
21	 -15.66 	80.3M  	0:02.76	Qxa5 Bc6 Rxf8 Nd7 Rf4 f1=Q Nxe7 Qxf4 Nf5+ Qxf5+ Kxf5 g1=Q Re1 Rf2+ Ke6 Rf6+ Ke7 Rf1 Re2 Rxd1 Qd8 Qf1 Kxd6+ Ndf6 Qh8+ Nh5 Rb2 g2 Rxg2 Qxg2 Kxc6 Ne5+ Kc5 Qe4 Kb5 Kg3 Qe8 d3 Qe7
20	 -15.58 	67.0M  	0:02.30	Qxa5 Bc6 Rxf8 Nd7 Rf4 f1=Q Nxe7 Qxf4 Nf5+ Qxf5+ Kxf5 g1=Q Re1 Rf2+ Ke6 Rf6+ Ke7 Rf1 Re6 Rxd1 Kxd6 Rc1 Qd8+ Ndf6 Qh8+ Nh5 Kc7 Qh2 Qd8+ Ngf6
19	 -14.62 	44.8M  	0:01.54	Qb8 Ne6 Rxe6 f1=Q Qxf8 Qd3+ Rf5 g1=Q Qxe7+ Nf6 Nxf6 Qxf5+ Kxf5 Rf2+ Kg6 Qxd1 Kxg7 Rf5 Ne4+ Kg4 Rg6+ Kf3 Nxd6 Qh1 Nxf5 Rh7+ Kf8 Rxe7 Nxe7 g2
18	 -13.49 	31.8M  	0:01.10	Qb8 Ne6 Rxe6 f1=Q Qxf8 Qd3+ Rf5 g1=Q Qxe7+ Nf6 Nxf6 Qxf5+ Kxf5 Rf2+ Kg6 Qxd1 Kxg7 Rf5 Nh7+ Kg4 Rg6+ Kf3 Ng5+ Rxg5 Qxg5 Qc7+ Kg8 Qd7 Qf6+ Kg2 Rg7 Qe8+ Qf8 Qxf8+ Kxf8 Qg1
17	 -12.49 	16.7M  	0:00.58	Qxa5 Bc6 Rxf8 Nd7 Qd8 Nxf8+ Qxf8 f1=Q Qxe7+ Nf6 Re6 g1=Q Nxf6 Qd3+ Kxg7 Qdxd1 Nxd5+ Kh5 Nf4+ Kg4 Nxh3 Rxh3 Qxd6
16	 -13.41 	14.6M  	0:00.51	Qxa5 Bc6 Rxf8 Nd7 Rf5 Nge5+ Rexe5 Nxe5+ Rxe5 dxe5 Qb4 g1=Q Ne3 Be8+ Kxg7 g2 Qxe7+ Kg3 Qxe5+ Kf3 Qxd5+ Kxe3 Qb3+ d3 Qe6+ Kd2 Qa2+ Kc3 Qa3+ Kd4 Qb2+ Ke4 Qb4+ Ke3 Qb6+ Kf3 Qf6+ Ke2 Qb2+ d2
15	 -8.91 	3.96M  	0:00.14	Qxa5 Bc6 Qd8 f1=Q Qxf8 Be8+ Qxe8 Qxf4 Qxe7+ Nf6 Re1 Qg5+ Kf7 Qh5+ Kxg7 Qg5+ Kf7 g1=Q Rxg1
14	 -9.38 	1.35M  	0:00.05	Qxa5 Bc6 Rxf8 Nd7 Qd8 Nxf8+ Qxf8 f1=Q Qxe7+ Nf6 Rxg2 Rxg2 Kxg7 Rd2 Nxf6 Rxd1 Nxd5+ Kh5 Qe6 Bxd5 Qxd5+ Kg4 Qxd6 Qf5
13	 -7.72 	539672	0:00.02	Qxa5 g1=Q Nxe7 Bxe7 Qxa8 g2
12	 -8.66 	359515	0:00.02	Qxa5 g1=Q Nxe7 Bxe7 Qxa8 g2
11	 -9.61 	317093	0:00.01	Qxa5 g1=Q Nxe7 Bxe7 Qxa8 g2
10	 -9.76 	279207	0:00.01	Qxa5 g1=Q Nxe7 Bxe7 Qxa8 g2
9	 -10.35 	215818	0:00.01	Qxa5 f1=Q Qd2 g1=Q
8	 -10.98 	164188	0:00.01	Qxa5 g1=Q Rxf8 f1=Q
7	 -13.02 	92368  	0:00.01	Qxa5 f1=Q Rf5 Ne5+ Rexe5 dxe5 Rxf1 gxf1=Q Qxa8 g2
6	 -12.38 	55265  	0:00.00	Qxa5 f1=Q Rf5 Ne5+ Rexe5 dxe5
5	 -12.64 	25394  	0:00.00	Nxe7 Bxe7 Qxa5 f1=Q Rxf1
4	 -11.81 	10245  	0:00.00	Qxa5 f1=Q Qxa8 Qxe2
3	 -11.81 	7998    	0:00.00	Qxa5 f1=Q Qxa8
2	 -10.98 	5045    	0:00.00	Qxa5 g1=Q
1	 -10.98 	3100    	0:00.00	Qxa5 g1=Q Rxf8 f1=Q Rxf1 Rxe2
0	# ``````

stevenaaus
Posts: 604
Joined: Wed Oct 13, 2010 7:44 am
Location: Australia
Contact:

### Re: Simple mate in 6 that gives some engines trouble

Great position.
Phalanx and Toga both find it in a short time.. depth 11 or 12.

JVMerlino
Posts: 1043
Joined: Wed Mar 08, 2006 9:15 pm
Location: San Francisco, California

### Re: Simple mate in 6 that gives some engines trouble

Myrddin with one core on a 6-year old laptop announces mate in 40 seconds:

Code: Select all

`````` 9  -1628     46       489272 b6a5? f2f1Q (1045 KNPS)
9  -1644     60       687706 b6a5? f2f1Q (1129 KNPS)
9  -1676     70       848525 b6a5? f2f1Q (1207 KNPS)
9  -1724     79      1023146 b6a5? f2f1Q (1285 KNPS)
9  -1612     95      1290125 b6a5 f2f1Q a5d2 c5e6 f4g4 (1353 KNPS)
10  -1596    132      1782071 b6a5! (1341 KNPS)
10  -1580    146      1998103 b6a5! (1361 KNPS)
10  -1548    151      2076152 b6a5! (1370 KNPS)
10  -1532    265      3687605 b6a5 c5d3 a5d2 g2g1Q f4f8 d3e5 e2e5 g4e5 (1388 KNPS)
11  -1516    395      5436923 b6a5! (1375 KNPS)
11  -1500    451      6212529 b6a5! (1375 KNPS)
11  -1468    504      6922551 b6a5! (1371 KNPS)
11  -1436    585      8032685 b6a5 g2g1Q g8e7 f8e7 a5a8 g3g2 d1f2 g1b1 g6f7 h3f3 f4f3 g2g1Q f7e7 h2f2 f3f2 g4f2 a8d5 (1370 KNPS)
12  -1420   1139     15680187 b6a5! (1376 KNPS)
12  -1404   1240     17090255 b6a5! (1377 KNPS)
12  -1372   1371     18836787 b6a5! (1373 KNPS)
12  -1324   1467     20118181 b6a5! (1371 KNPS)
12  -1408   1553     21419367 b6a5 f2f1Q a5d2 c5e6 e2e6 g2g1Q f4f1 h2d2 f1g1 g4e5 g6f5 g7g6 e6g6 e5g6 f5g6 (1379 KNPS)
12  -1260   1723     23911703 g8h6! g4e5 b6a5 (1387 KNPS)
12  -1180   1732     24033311 g8h6! (1386 KNPS)
12  -1084   1742     24148391 g8h6! (1386 KNPS)
12   -972   1751     24299403 g8h6! (1387 KNPS)
12   -844   1753     24306869 g8h6! (1386 KNPS)
12   -700   1753     24312308 g8h6! (1386 KNPS)
12  -2437   1918     26516523 g8h6 g7h6 b6a5 f2f1Q f4f5 f1f5 g6f5 g2g1Q e2e1 e7e6 f5g6 g4e5 e1e5 d6e5 a5d8 h4g4 d8f8 (1382 KNPS)
12  -1408   3185     44011651 b6a5 f2f1Q g8e7 (1381 KNPS)
13  -1424   3306     45840706 b6a5? f2f1Q (1386 KNPS)
13  -1392   3604     50332140 g8h6! e7d6 g8e7 (1396 KNPS)
13  -1376   3609     50382717 g8h6! (1395 KNPS)
13  -1344   3615     50458787 g8h6! (1395 KNPS)
13  -1296   3629     50652590 g8h6! (1395 KNPS)
13  -1232   3643     50829885 g8h6! (1395 KNPS)
13  -1152   3653     50942935 g8h6! (1394 KNPS)
13  -1056   3668     51167967 g8h6! (1394 KNPS)
13   -944   3671     51213364 g8h6! (1394 KNPS)
13   -816   3675     51244454 g8h6! (1394 KNPS)
13   -672   3678     51264956 g8h6! (1393 KNPS)
13  32756   4048     56338252 g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 g2g1Q f5h5 (1391 KNPS)(Mate in 6)
14  32756   4112     57159144 g8h6 g7h6 e2e5 d6e5 b6f6 e7f6 d1e3 d4e3 f4f5 g2g1Q f5h5 (1389 KNPS)(Mate in 6)
``````