7 steps to heaven. 7 testpositions of variable difficulty!

[George Tsavdaris]

Here are 7 testpositions of the past to test the new monsters.
They are easy, medium and some are hard.



•Easy. Don't let your engine to make more than 5 seconds for this.
1...Nc3!! wins.
[d]6k1/3p2p1/3P2Pp/ppp5/3pn2P/1P3K2/1PP2PP1/3N4 b - - 0 1



•Easy but some computers had problems on this.
1.Nxd3!! wins.
[d]8/8/7K/8/p1p5/2Bp4/pn1N4/k3N3 w - - 0 1



•Hard. Computers had many difficulties not capturing with the Bishop on c5 here. In the 1st or 2nd move.
1.Bf8!! wins! With the plan 1...Bc7 2.Kxc5(and not Bxc5?) Bd8 3.Bg7! +-
[d]1b6/3kB3/8/1KpPp2p/4Pp1P/5P2/8/8 w - - 0 1



•Hard. The text move really wins but computers can't see it easily.
1...Rxb3!! wins! If black plays any other move, then white plays 2.Bc2 locking the position and assuring the draw.
[d]1r6/4k3/r2p2p1/2pR1p1p/2P1pP1P/pPK1P1P1/P7/1B6 b - - 0 1



•Very hard. If computers had the slightest ability of planning, then they would solve it in seconds.
1.Ke8! or 1.Ke7! wins! All other moves like e.g 1.Kxf7? or Kg7? etc only draw.
[d]5K2/k4p1p/5p1p/1p3p2/bP6/1p6/1P5p/7B w - - 0 1



•Very hard. A resulting position of the famous WAC 230, after the supposedly drawing ...exf5 move. (The whole line is 1...Rb4!! 2.cxb4 a4 3.b5+ Kxb5 4.Ba3 c3 5.Re2 Kc4 6.f4 Kxd4 7.f5 exf5 8.e6)
Since after ...exf5 e6 that had been analyzed, all lines had Kd3 or even Kc4 with long lines that eventually drew. But all miss the winning move: ...b2!! wins. So WAC 230 is correct after all.
That leads to one of the most interesting endgames i've seen. I hope i was not wrong on my analysis since it was made before 4 years with much weaker engines than today.
1...b2!! wins.
[d]2b5/8/4P1p1/3p1pP1/p2k4/Bpp3K1/4R3/8 b - - 0 1



•Very hard. A known classic anticomputer position of the past.
1.e6!! wins.
[d]q6r/p1p1pNb1/PpPp1p2/1P1PPPp1/B5Pp/4k2P/1RK5/8 w - - 0 1

[Jouni]

I only tried last one.

Analysis by Houdini 3 x64 T:

1.e6 Rg8 2.Kb3 Kf4 3.Kc4 Kg3 4.Rb3+ Kg2 5.Rc3 Qb8 6.Bc2 Qc8 7.Bd1 Qe8 8.Bc2 Kh2 9.Re3 Kg2 10.Kb4 Kf2 11.Rc3 Qc8 12.Be4 Rf8 13.Rd3 Qe8 14.Rf3+ Kg1 15.Re3 Kh2 16.Bc2
-+ (-5.14) Depth: 19/55 00:00:21 68696kN

Analysis by Houdini 3 x64:

1.Rb3+ Kf2 2.e6 Rf8 3.Rd3 Kg2 4.Bb3 Rg8 5.Kc3 Qb8 6.Kb4 Qe8 7.Rc3 Rf8 8.Bc2 Qb8 9.Be4+ Kh2 10.Bc2 Qe8 11.Rd3 Rg8 12.Re3 Kg2 13.Be4+ Kg1 14.Rc3
-+ (-5.14) Depth: 22/86 00:02:36 476mN

Alternative solution?

[George Tsavdaris]

I only tried last one.

Analysis by Houdini 3 x64 T:

1.e6 Rg8 2.Kb3 Kf4 3.Kc4 Kg3 4.Rb3+ Kg2 5.Rc3 Qb8 6.Bc2 Qc8 7.Bd1 Qe8 8.Bc2 Kh2 9.Re3 Kg2 10.Kb4 Kf2 11.Rc3 Qc8 12.Be4 Rf8 13.Rd3 Qe8 14.Rf3+ Kg1 15.Re3 Kh2 16.Bc2
-+ (-5.14) Depth: 19/55 00:00:21 68696kN

Analysis by Houdini 3 x64:

1.Rb3+ Kf2 2.e6 Rf8 3.Rd3 Kg2 4.Bb3 Rg8 5.Kc3 Qb8 6.Kb4 Qe8 7.Rc3 Rf8 8.Bc2 Qb8 9.Be4+ Kh2 10.Bc2 Qe8 11.Rd3 Rg8 12.Re3 Kg2 13.Be4+ Kg1 14.Rc3
-+ (-5.14) Depth: 22/86 00:02:36 476mN

Alternative solution?

I'm not sure, that's why i haven't said it is the only move that wins as in all the other positions, but after 1.Rb3+ Ke4(and not Kf2 Houdini gives) white loses a pawn and i believe the win slips away.

[IGarcia]

•Easy. Don't let your engine to make more than 5 seconds for this.
1...Nc3!! wins.
[d]6k1/3p2p1/3P2Pp/ppp5/3pn2P/1P3K2/1PP2PP1/3N4 b - - 0 1

This one... I saw it in a book some time ago, but cant recall wich one. Was in a real (human) game, still cant find the game in my database :S

The funny thing is i kno Nc3 wins because it will get a unstopable a-pawn if sacrifice is accepted.

Any help about the game it belongs?

Ignacio

[George Tsavdaris]

•Easy. Don't let your engine to make more than 5 seconds for this.
1...Nc3!! wins.
[d]6k1/3p2p1/3P2Pp/ppp5/3pn2P/1P3K2/1PP2PP1/3N4 b - - 0 1

This one... I saw it in a book some time ago, but cant recall wich one. Was in a real (human) game, still cant find the game in my database :S

The funny thing is i kno Nc3 wins because it will get a unstopable a-pawn if sacrifice is accepted.

Any help about the game it belongs?

In the 41th move of the game i've posted below.

Yet, the one i posted is a slightly modified position.
The original with the same solution is:
[d]6k1/6p1/6Pp/ppp5/3pn2P/1P3K2/1PP2P2/3N4 b - - 0 41

[Event "Olympiad"]
[Site "Haifa (Israel)"]
[Date "1976.??.??"]
[Round "13"]
[White "Bonner Gerald (SCO)"]
[Black "Medina-Garcia Antonio (ESP)"]
[Result "0-1"]
[ECO "C50"]
[WhiteElo "2225"]
[BlackElo "2253"]
[Annotator ""]
[Source ""]
[Remark ""]

1.e4 e5 2.Bc4 Nc6 3.Nc3 Nf6 4.d3 Bc5 5.Nf3 d6 6.Bg5 Na5 7.Bb3
Nxb3 8.axb3 c6 9.d4 exd4 10.Nxd4 h6 11.Bh4 O-O 12.O-O Re8 13.Nf5
Bxf5 14.exf5 d5 15.Qd3 Qd6 16.Rfe1 Ng4 17.Bg3 Qd7 18.h3 Nf6 19.Be5
Be7 20.Re2 Nh7 21.Rae1 Rad8 22.Qf3 Bf6 23.Bxf6 Rxe2 24.Rxe2 Nxf6
25.g4 b5 26.Qf4 a5 27.Nd1 c5 28.h4 Re8 29.Rxe8+ Qxe8 30.Kf1 d4
31.g5 Nd5 32.Qd6 Qe4 33.g6 Nf6 34.Qb8+ Qe8 35.Qg3 Ne4 36.Qg4
Nd2+ 37.Kg2 Qe1 38.Qf4 fxg6 39.fxg6 Qe4+ 40.Qxe4 Nxe4 41.Kf3
Nc3 42.bxc3 a4 43.cxd4 cxd4 44.c3 a3 0-1

[IGarcia]

Yes thats the game, with less pawns, and the book is

"101 consejos sobre el final, Steve Giddins"


http://books.google.com.ar/books?id=LK4 ... fa&f=false

well, now I will give a try to the other positions you posted.
Thanks!!

[ernest]

...b2!! wins. So WAC 230 is correct after all.
That leads to one of the most interesting endgames i've seen. I hope i was not wrong on my analysis since it was made before 4 years with much weaker engines than today.
1...b2!! wins.
[d]2b5/8/4P1p1/3p1pP1/p2k4/Bpp3K1/4R3/8 b - - 0 1

Wrong!
After 1...b2 2.Bxb2 cxb2 3.e7! saves the draw
(but not 3.Rxb2?)

[Eelco de Groot]

...b2!! wins. So WAC 230 is correct after all.
That leads to one of the most interesting endgames i've seen. I hope i was not wrong on my analysis since it was made before 4 years with much weaker engines than today.
1...b2!! wins.
[d]2b5/8/4P1p1/3p1pP1/p2k4/Bpp3K1/4R3/8 b - - 0 1

Wrong!
After 1...b2 2.Bxb2 cxb2 3.e7! saves the draw
(but not 3.Rxb2?)

Are you sure that e7 is drawing?

With my Stockfish "Chessbase" Hybrid clone, just joking about that, it is admittedly a bit selective but it has almost standard Stockfish 2.3.2 eval I can go to depth 36 with it on an old Athlon in under 4 hours with a small hashtable:


[d]2b5/8/4P1p1/3p1pP1/p2k4/6K1/1p2R3/8 w - -

Engine: Stockfish 2.3.1 Hybrid, Chessbase Open Source Release Candidate 145 Athlon 2009 MHz, only 1 thread, 128 MB
by Tord Romstad, Marco Costalba and Joona Kiiski


28/63 5:20 -0.96 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Ke5 Bd7
6.Rc2+ Kb4 7.Rb2+ Ka5 8.Ra2 Bc6
9.Ra1 d4 10.Kxd4 f4 11.Ra2 f3 12.Ra1 Bb5
13.Ke3 Be2 14.Kf2 Kb4 15.Rb1+ Kc5
16.Rc1+ (249.532.936) 778

29/69 8:44 -1.45 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Ke5 Bd7
6.Rc2+ Kb4 7.Rb2+ Ka5 8.Ra2 Bc6
9.Ra1 f4 10.Kxf4 Bb5 11.Ke5 Bc4
12.Kf6 Bd3 13.Ra2 Kb4 14.Rb2+ Kc3
15.Rb8 a3 16.Ra8 (410.166.465) 781

30/69 16:25 -1.45 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Ke5 Bd7
6.Rc2+ Kb4 7.Rb2+ Ka5 8.Ra2 Bc6
9.Ra1 f4 10.Kxf4 Bb5 11.Ke5 Bc4
12.Kf6 Bd3 13.Ra2 Kb4 14.Rb2+ Kc3
15.Rb8 a3 16.Ra8 (769.795.733) 781

31/69 25:19 -1.41 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Ke5 Bd7
6.Rc2+ Kb4 7.Rb2+ Ka5 8.Ra2 Bc6
9.Ra1 f4 10.Kxf4 Bb5 11.Ke5 Bc4
12.Kf6 Bd3 13.Rd1 Be4 14.Rc1 a3
15.Rc8 Kb4 16.Rb8+ (1.196.675.880) 787

32/78 35:03 -1.69 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3
10.Rh6 a2 11.Rh1 Bd5 12.Ra1 Bb3
13.g6 Ke6 14.g7 Kf6 15.Rg1 Bd5
16.Ra1 (1.671.561.611) 794

33/78 40:06 -1.85 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3
10.Rh6 a2 11.Rh1 Bd5 12.Ra1 Bb3
13.g6 Ke6 14.g7 Kf6 15.Rg1 Bd5
16.Ra1 (1.919.255.143) 797

34/78 121:11 -1.73 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3
10.Rh6 a2 11.Rh1 Bd5 12.Ra1 Bb3
13.g6 Ke6 14.g7 Kf6 15.Rg1 Bd5
16.Ra1 (5.926.336.764) 815

35/78 190:56 -1.73 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3
10.Rh6 a2 11.Rh1 Bd5 12.Ra1 Bb3
13.g6 Ke6 14.g7 Kf6 15.Rg1 Bd5
16.Ra1 (9.533.567.332) 832

36/88 220:19 -1.45 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3
10.Rh6 a2 11.Rh1 Bd5 12.Ra1 Bb3
13.g6 Ke6 14.g7 Kf6 15.Rg1 Bd5
16.Ra1 (11.009.081.370) 832

The engine has e7 as second move always, but so far has rejected it each time. It is not totally clear this is a losing score for 3. Rxb2 though. Maybe an engine that uses endgame table bases and that can go deeper can see this better.

[Eelco de Groot]

I stopped the engine after completion of 37 plies with still 3. Rxb2 as best, although the engine thought very long about 3. e7

[FEN "2b5/8/4P1p1/3p1pP1/p2k4/Bpp3K1/4R3/8 b - -"]

1... b2 2. Bxb2 cxb2 *

37/88 605:32 -1.41 3.Rxb2 Bxe6 4.Kf4 Kc5 5.Rc2+ Kd6
6.Rb2 Bd7 7.Rb8 d4 8.Rg8 Be6 9.Rxg6 a3 (30.086.449.037) 828

best move: Re2xb2 time: 620:35.094 min n/s: 828.093 nodes: 30.086.449.037

[peter]

But I think Ernest is right, Eelco.

Try to show this line to your Stockfish :

1... b2 2. Bxb2 cxb2 3. e7 b1=Q 4. e8=Q Qg1+ 5. Kf3 Qf1+ 6. Kg3 f4+ 7. Kh2 Qh3+ 8. Kg1 Qg3+ 9. Kh1 Qf3+ 10. Kg1 Bd7 11. Qe5+

Then any losing line after 3.Rxb2? like this one:

1... b2 2. Bxb2 cxb2 3. Rxb2 Bxe6 4. Kf4 Kc5 5. Rc2+ Kd6 6. Rb2 Bd7 7. Rb8 Kc5

After backward solving of both (3...e7 first, 3...Rxb2 second), I get this output on two variants MV mode:

Code: Select all

2b5/8/4P1p1/3p1pP1/p2k4/6K1/1p2R3/8 w - - 0 1

Analysis by Stockfish 2.3.1 JA 64bit SSE4.2:

1. =  (-0.16): 3.e7 b1D 4.e8D Dg1+ 5.Kf3 Df1+ 6.Kg3 f4+ 7.Kh2 Dh3+ 8.Kg1 Dg3+ 9.Kh1 Df3+ 10.Kg1 Ld7 11.De5+ Kd3 12.Tf2 Dg4+ 13.Kh2 Le6 14.Txf4 Dh3+ 15.Kg1 Dg3+ 16.Kh1 De3 17.Dxe3+ Kxe3 18.Txa4 d4 19.Kg2 d3 20.Kf1 Ld5 21.Ta7 Le4 22.Ta3 Lf5 23.Ke1 Le6 24.Tc3 Lg8 25.Kf1 Lf7 26.Ta3 Lc4 27.Ke1 Ld5 28.Kf1 Lc4 
2. -+  (-4.44): 3.Txb2 Lxe6 4.Kf4 Kc5 5.Tc2+ Kd6 6.Tb2 Ld7 7.Tb6+ Lc6 8.Tb1 d4 9.Td1 Lb5 10.Txd4+ Kc5 11.Td1 Lc4 12.Ta1 Kb4 13.Tb1+ Lb3 14.Ta1 a3 15.Ke5 Lc4 16.Kf6 f4 17.Tb1+ Kc5 18.Ta1 a2 19.Kxg6 f3 20.Kf6 f2 

Same with H3 and 6MOB:

2b5/8/4P1p1/3p1pP1/p2k4/6K1/1p2R3/8 w - - 0 1

Analysis by Houdini 3 Pro x64:

1. =  (-0.07): 3.e7 b1D 4.e8D Dg1+ 5.Kf3 Df1+ 6.Kg3 f4+ 7.Kh2 Dh3+ 8.Kg1 Dg3+ 9.Kh1 Df3+ 10.Kg1 Ld7 11.De5+ Kd3 12.Tf2 Dg4+ 13.Kf1 Dh3+ 
2. -+  (-3.06): 3.Txb2 Lxe6 4.Kf4 Kc5 5.Tc2+ Kd6 6.Tb2 Ld7 7.Tb7 d4 8.Ta7 Lb5 9.Tg7 Le8 10.Tg8 Ke7 11.Th8