Endgame that Crafty dont understand at depth 30

[kiroje]

I have been really happy with the new Crafty engine, and used it for analysing my games.

In one of my games this position came up, and after some serious thought Crafty dont really get it(or possibly I dont get it )

[d] 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 1 40

Crafty 22.5 in SCID
Depth: 30 Nodes: 63382298K (2088 kn/s)
Score: +2.18 Time: 30357.42 seconds
40. dxc6+ Ke6 41. h4 Nb5 42. Be2 Nc7 43. Bc4+ Ke7 44. Kd3 f6 45. Bg8 Ne8 46. Kd4 Nc7 47. Bb3 Nb5+ 48. Ke3 Nc7 49. Kd3 Ke8 {HT}

Im quite sure that dxc6+ would result in a fortress like position where black plays f6 and goes back and forth with his king on e8 and e7.

So the +2.18 should be 0.00 or something close to that.

Im i right or is there someone that can disprove it ?

[glorfindel]

You are probably right about the position being equal, though white could also try g4 after dxc6+ to avoid the fortress.

Fortresses like that are hard to evaluate for chess engines, not only Crafty, as was recently shown also in the final position of the 7th game Anand-Kramnik. I analysed the position with Shredder Classic, and it also gives about +2.20.

I am not sure this is such a big problem, as long as the engine plays the correct defence as black and holds the draw. That it evaluates white to be better is normal, and everyone would prefer to play white and not black in this position. So in my opinion it should show a positive score, I can not say how much though.

[bob]

I have been really happy with the new Crafty engine, and used it for analysing my games.

In one of my games this position came up, and after some serious thought Crafty dont really get it(or possibly I dont get it )

[d] 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 1 40

Crafty 22.5 in SCID
Depth: 30 Nodes: 63382298K (2088 kn/s)
Score: +2.18 Time: 30357.42 seconds
40. dxc6+ Ke6 41. h4 Nb5 42. Be2 Nc7 43. Bc4+ Ke7 44. Kd3 f6 45. Bg8 Ne8 46. Kd4 Nc7 47. Bb3 Nb5+ 48. Ke3 Nc7 49. Kd3 Ke8 {HT}

Im quite sure that dxc6+ would result in a fortress like position where black plays f6 and goes back and forth with his king on e8 and e7.

So the +2.18 should be 0.00 or something close to that.

Im i right or is there someone that can disprove it ?

First question would be do you have any program that _does_ score that as 0.0?? Some might if they don't like the side they start on, and then go for a repetition. But very few recognize fortresses, even fewer do it right. All the way to the top and Rybka in fact... That's a simple idea, but there are so many variations of a fortress that nobody is willing to spend the evaluation time necessary to recognize all types...

[kiroje]

First question would be do you have any program that _does_ score that as 0.0?? Some might if they don't like the side they start on, and then go for a repetition. But very few recognize fortresses, even fewer do it right. All the way to the top and Rybka in fact... That's a simple idea, but there are so many variations of a fortress that nobody is willing to spend the evaluation time necessary to recognize all types...

I havent checked with other programs after the new Crafty version, I was just wondering.

I know the problem with understanding draw positions, so I wondered if it was an idea(and probably seen before) doing something like this

If the same piece for each side is moved in the PV (kings for example in this position) then lower the score by the winning side some margin each 4. ply ?

Margin could be 0.2 or something like that and plynumber could be larger/smaller.

just so a 20 ply PV with kings shuffling around would lower the score ?

Just a thought(and someone probably thought of it before and can tell me why its an insanely stupid idea)

[Dann Corbit]

Quite often, an engines analysis will reveal a draw, even though the score does not reveal it.

For instance, elsewhere, this position came up for analysis:
[d]8/8/5p2/4p1k1/R5p1/5bK1/8/8 w - - c0 "Is it a draw?";

Now, none of the 12 engines I tried knew it was a draw, but all of them told me that it was. The analysis for each and every engine looks like this:

Code: Select all

Analysis from Q:\epd\sub\drawq.epd   
11/26/2008 2:41:27 PM Level: Tournament Game in one Minute
Analyzing engine: Glaurung_2_1_x64_EM64T

1) "Is it a draw?";     
    Avoid move: 
    Best move (Glaurung_2_1_x64_EM64T): Ra4-a5
    Not found in: 03:00
      2	00:00	          46	196	-3.27	Ra4a1 f6f5
      2	00:00	         103	440	-2.68	Ra4a5 Kg5f5
      3	00:00	         172	735	-2.70	Ra4a5 Kg5f5 Ra5a1
      4	00:00	         439	1.876	-2.64	Ra4a5 Kg5f5 Ra5a1 Bf3d5
      5	00:00	       1.014	4.333	-2.68	Ra4a5 Kg5f5 Ra5a4 Bf3e4 Ra4a1
      6	00:00	       1.791	7.192	-2.64	Ra4a5 Kg5f5 Ra5a4 Bf3e4 Ra4a1 Be4d5
      7	00:00	       6.071	24.381	-2.62	Ra4a5 Kg5f5 Ra5a4 Bf3e2 Ra4a2 Be2c4 Ra2f2+ Kf5g5
      8	00:00	       9.736	39.100	-2.56	Ra4a5 Kg5f5 Ra5a4 Bf3e2 Ra4a2 Be2d3 Ra2f2+ Kf5g5 Rf2b2
      9	00:00	      42.997	172.678	-2.64	Ra4a5 Bf3e4 Ra5b5 Be4f5 Rb5b3 Bf5e6 Rb3b5 Kg5f5 Rb5b2
     10	00:00	      50.556	203.036	-2.64	Ra4a5 Bf3e4 Ra5b5 Kg5f5 Rb5b4 Be4f3 Rb4a4 Bf3e2 Ra4a2 Be2f3
     11	00:00	      57.194	215.826	-2.64	Ra4a5 Bf3e4 Ra5b5 Kg5f5 Rb5b4 Be4f3 Rb4a4 Bf3e2 Ra4a2 Be2d3 Ra2a1
     12	00:00	      89.226	336.701	-2.64	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6f5 Rc5c3 Bf5e4 Rc3c5 Kg5f5 Rc5c1 Be4d5
     13	00:00	     144.965	517.732	-2.70	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6f5 Rc5c3 Bf5e4 Rc3c5 Kg5f5 Rc5a5 Be4f3 Ra5a1
     14	00:00	     206.951	699.158	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6f5 Rc5c1 Bf5e6 Rc1c5 Kg5f5 Rc5a5 Kf5e4 Ra5a4+ Ke4d3 Ra4a1
     15	00:00	     302.975	971.073	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6h7 Rc5a5 Bh7d3 Ra5d5 Bd3e2 Rd5d2 Be2c4 Rd2c2 Bc4d5 Rc2h2
     16	00:00	     506.485	1.476.632	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6h7 Rc5a5 Bh7d3 Ra5d5 Bd3e2 Rd5a5 Kg5f5 Ra5a2 Be2f3 Ra2h2 e5e4 Rh2h5+ Kf5e6
     17	00:00	     759.151	2.029.815	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6h7 Rc5d5 Bh7c2 Rd5b5 Kg5f5 Rb5b4 Bc2e4 Rb4c4 Be4f3 Rc4a4 e5e4 Ra4a5+ Kf5e6
     18	00:00	   1.036.433	2.461.836	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6h7 Rc5d5 Bh7c2 Rd5b5 Kg5f5 Rb5b4 Bc2e4 Rb4b2 Be4d5 Rb2h2 Bd5f3 Rh2h4 Kf5e4
     19	00:00	   1.301.293	2.780.540	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6h7 Rc5d5 Bh7c2 Rd5b5 Kg5f5 Rb5b4 Bc2e4 Rb4b2 Be4d5 Rb2h2 Bd5f3 Rh2h6 Kf5e6 Rh6h2
     20	00:00	   2.280.460	3.750.756	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a4 Bd5e4 Ra4c4 Be4f3 Rc4a4 e5e4 Ra4a5+ Kf5e6
     21	00:00	   2.839.463	4.044.819	-2.58	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a4 Bd5e4 Ra4c4 Be4f3 Rc4a4 e5e4 Ra4a5+ Kf5e6
     22	00:00	   3.960.850	4.537.056	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a2 Kf5g5 Ra2a5 Bb5c4
     23	00:01	   5.186.376	5.040.209	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a2 Kf5g5 Ra2a5 Bb5c4 Ra5a1
     24	00:01	   7.174.516	5.544.448	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5e2 Ra7a4 Kf5g5 Ra4a5 Be2c4
     25	00:01	  10.245.474	6.026.749	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5e2 Ra7a4 Kf5g5 Ra4a5 Be2c4 Ra5a1
     26	00:02	  14.295.767	6.454.070	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5c4 Ra7a4 Bc4e2 Ra4a5 Kf5e4 Ra5a4+ Ke4e3 Ra4a3+ Ke3d4
     27	00:02	  20.129.436	6.791.307	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5c4 Ra7a4 Bc4e2 Ra4a5 Kf5e4 Ra5a4+ Ke4e3 Ra4a3+ Ke3d4 Ra3a4+ Kd4d5
     28	00:04	  29.557.214	7.149.785	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5e2 Ra7a4 Be2d1 Ra4a1 Bd1b3 Ra1f1+ Kf5g5 Rf1b1 Bb3d5 Rb1a1
     29	00:05	  44.635.186	7.510.547	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5e2 Ra7a4 Be2d1 Ra4a1 Bd1c2 Ra1h1 Bc2e4 Rh1h2 Be4d3 Rh2f2+ Kf5g5
     30	00:09	  72.969.743	7.795.912	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5c6 Ra5a1 Bc6b5 Ra1a7 Bb5e2 Ra7a4 Be2d1 Ra4a1 Bd1c2 Ra1h1 Bc2e4 Rh1h2 Be4d3 Rh2f2+ Kf5g5 Rf2a2
     31	00:13	 110.203.325	8.000.241	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Bf3d5 Ra6a5 Bd5b3 Ra5a1 Kf5g5 Ra1a5 Bb3c2 Ra5b5 Bc2e4 Rb5c5 Be4d3 Rc5a5 Bd3f5 Ra5a1 Bf5e6 Ra1e1 Be6d5 Re1a1
     32	00:19	 157.331.879	8.140.101	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Kf2g3 Bc4e6 Ra5a6 Kg6f7 Ra6a7+ Kf7e8 Kg3f2 Be6d7 Ra7a5 Ke8e7 Kf2g3 Bd7e6 Ra5a7+ Ke7d6 Ra7a6+ Kd6d5 Ra6a1
     33	00:27	 228.500.363	8.233.653	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Ra5a4 Bc4e6 Ra4a6 Be6c8 Ra6a8 Bc8b7 Ra8a7 Bb7e4 Ra7a5 Kg6g5 Kf2g3 Be4d3 Ra5d5 Bd3c4 Rd5d1
     34	00:39	 329.535.811	8.349.442	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Ra5a4 Bc4e6 Ra4a6 Be6c8 Ra6a8 Bc8b7 Ra8a7 Bb7e4 Ra7a5 Kg6g5 Kf2g3 Be4d3 Ra5d5 Bd3e2 Rd5a5 Be2c4
     35	01:00	 508.511.535	8.475.474	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Ra5a4 Bc4e6 Ra4a6 Be6c8 Ra6a8 Bc8b7 Ra8a7 Bb7e4 Ra7a5 Kg6g5 Kf2g3 Be4d3 Ra5d5 Bd3e2 Rd5a5 Be2c4 Ra5a1
     36	01:30	 775.815.075	8.567.051	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Ra5a4 Bc4e6 Ra4a6 Be6c8 Ra6a8 Bc8b7 Ra8a7 Bb7e4 Ra7a5 Kg6g5 Kf2g3 Be4d3 Ra5d5 Bd3c4 Rd5c5 Bc4a6 Rc5a5 Ba6c4
     37	02:12	1.143.788.811	8.616.695	-2.56	Ra4a5 Bf3e4 Ra5b5 Be4g6 Rb5c5 Bg6b1 Rc5d5 Kg5f5 Rd5a5 Bb1e4 Ra5a4 Be4f3 Ra4a6 Kf5g6 Ra6a5 Bf3e2 Kg3f2 Be2c4 Ra5a4 Bc4e6 Ra4a6 Be6c8 Ra6a8 Bc8b7 Ra8a5 f6f5 Ra5b5 Bb7f3 Rb5xe5 f5f4 Re5e8 Bf3d5 Re8d8 g4g3+ Kf2g1 Bd5e4 Rd8f8 Kg6g5 Rf8c8
   11/26/2008 4:15:03 PM, Time for this analysis: 00:03:00, Rated time: 03:00

0 of 1 matching moves
11/26/2008 4:15:03 PM, Total time: 1:33:35 AM
Rated time: 03:00 = 180 Seconds

When you see a very long and deep search with no progress whatsoever, that is our clue that the position is almost certainly drawn.

Usually, you can also follow the pv (if it is long enough) and see the game of "ring-around-the-rosy" in action to confirm it.

That does not mean it is a certain draw. Sometimes, the engines (even the dreaded minnow of terror) can fail to find the right plan. But it means that the best thing that a very good chess problem solver can find is a draw.

[Ovyron]

[d]8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 0 1

Rybka 3:

18.01 0:20 +1.56 1.dxc6+ Ke7 2.Be2 h4 3.Bc4 Ke8 4.Kd2 Ke7 5.Kc3 f6 6.Kd3 Ke8 7.Kd4 Ke7 8.Ke3 (402.131) 19
19.01 0:32 +1.64 1.dxc6+ Ke7 2.h4 Kd8 3.Kd4 (611.120) 19
20.01 0:42 +1.64 1.dxc6+ Ke7 2.h4 Kd8 3.Kd4 Ne6+ 4.Kd5 Ke7 5.g3 Nc7+ 6.Kc4 Nb5 7.Be2 Nc7 8.Kd4 Ne6+ 9.Kd5 (779.502) 18
21.01 1:19 +1.84++ 1.dxc6+ (1.427.724) 18
21.01 1:24 +1.84 1.dxc6+ Ke7 2.h4 Kd8 3.Kd4 Ne6+ 4.Kd5 Nc7+ 5.Ke5 Ke7 6.Bd5 f6+ 7.Kd4 (1.519.123) 18

Doesn't see the draw either.

[bob]

First question would be do you have any program that _does_ score that as 0.0?? Some might if they don't like the side they start on, and then go for a repetition. But very few recognize fortresses, even fewer do it right. All the way to the top and Rybka in fact... That's a simple idea, but there are so many variations of a fortress that nobody is willing to spend the evaluation time necessary to recognize all types...

I havent checked with other programs after the new Crafty version, I was just wondering.

I know the problem with understanding draw positions, so I wondered if it was an idea(and probably seen before) doing something like this

If the same piece for each side is moved in the PV (kings for example in this position) then lower the score by the winning side some margin each 4. ply ?

Margin could be 0.2 or something like that and plynumber could be larger/smaller.

just so a 20 ply PV with kings shuffling around would lower the score ?

Just a thought(and someone probably thought of it before and can tell me why its an insanely stupid idea)

There was a program that did this. I don't recall for certain, but perhaps little goliath. The problem was it often saw "phantom draws" and stumbled into a dead loss from a position that was drawable, due to this kind of evaluation term. It found some drawish positions some missed, but it found some non-drawish positions that it thought were drawish and lost, which is not a good idea.

[Dirt]

I have been really happy with the new Crafty engine, and used it for analysing my games.

In one of my games this position came up, and after some serious thought Crafty dont really get it(or possibly I dont get it :wink: )

[d] 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 1 40

Crafty 22.5 in SCID
Depth: 30 Nodes: 63382298K (2088 kn/s)
Score: +2.18 Time: 30357.42 seconds
40. dxc6+ Ke6 41. h4 Nb5 42. Be2 Nc7 43. Bc4+ Ke7 44. Kd3 f6 45. Bg8 Ne8 46. Kd4 Nc7 47. Bb3 Nb5+ 48. Ke3 Nc7 49. Kd3 Ke8 {HT}

Im quite sure that dxc6+ would result in a fortress like position where black plays f6 and goes back and forth with his king on e8 and e7.

So the +2.18 should be 0.00 or something close to that.

Im i right or is there someone that can disprove it ?

After a while Toga prefers Kd4. Is that a draw? I'm unable to tell.

[sorcerers_apprentice]

I have been really happy with the new Crafty engine, and used it for analysing my games.

In one of my games this position came up, and after some serious thought Crafty dont really get it(or possibly I dont get it )

[d] 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 1 40

Crafty 22.5 in SCID
Depth: 30 Nodes: 63382298K (2088 kn/s)
Score: +2.18 Time: 30357.42 seconds
40. dxc6+ Ke6 41. h4 Nb5 42. Be2 Nc7 43. Bc4+ Ke7 44. Kd3 f6 45. Bg8 Ne8 46. Kd4 Nc7 47. Bb3 Nb5+ 48. Ke3 Nc7 49. Kd3 Ke8 {HT}

Im quite sure that dxc6+ would result in a fortress like position where black plays f6 and goes back and forth with his king on e8 and e7.

So the +2.18 should be 0.00 or something close to that.

Im i right or is there someone that can disprove it ?

HIARCS 12 MP does not see the draw either.

Code: Select all

26/56  3:51   +1.78    1.dxc6+ Ke6 2.g3 f6 3.Kd4 Nb5+ 4.Kc4 Nc7 
                       5.Be2 Ke7 6.Kc3 Kd8 7.Kd4 Ke7 8.Bc4 Ke8 
                       9.h4 Ke7 10.Bd5 Nb5+ 11.Ke3 Nc7 
                       12.Bc4 Ke8 13.Be2 Nd5+ 14.Kd4 (221.575.038) 955 
                       TB:6.357 

best move: d5xc6 time: 6:00.987 min  n/s: 929.469  nodes: 335.193.623 TB: 6.357

[beachknight]

I have been really happy with the new Crafty engine, and used it for analysing my games.

In one of my games this position came up, and after some serious thought Crafty dont really get it(or possibly I dont get it )

[d] 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 1 40

Crafty 22.5 in SCID
Depth: 30 Nodes: 63382298K (2088 kn/s)
Score: +2.18 Time: 30357.42 seconds
40. dxc6+ Ke6 41. h4 Nb5 42. Be2 Nc7 43. Bc4+ Ke7 44. Kd3 f6 45. Bg8 Ne8 46. Kd4 Nc7 47. Bb3 Nb5+ 48. Ke3 Nc7 49. Kd3 Ke8 {HT}

Im quite sure that dxc6+ would result in a fortress like position where black plays f6 and goes back and forth with his king on e8 and e7.

So the +2.18 should be 0.00 or something close to that.

Im i right or is there someone that can disprove it ?

Crafty 22.01 chessbase couldnt find either:

Code: Select all

33: 8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4 - Deep Fritz 11
8/2nk1p2/p1p3p1/P1PP1p1p/5P2/4KB1P/6P1/8 w - - 0 1

Analysis by Crafty 22.01:

 +-  (1.98)   Depth: 16   00:00:25  8324kN
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Bd5 Nb5+ 45.Kd3 Nc7 46.Bc4 Ke7 47.Ke3 f6 48.Bg8 Ke8 49.Bb3 Ke7 50.Bc4 Kf8 51.Bd3 
  +-  (1.98)   Depth: 17   00:00:33  12408kN
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Bd5 Nb5+ 45.Kd3 Nc7 46.Bc4 Ke7 47.Ke3 f6 48.Bg8 Ke8 49.Bb3 Ke7 50.Bc4 Kf8 51.Bd3 Nd5+ 
  +-  (1.98)   Depth: 18   00:00:40  18909kN, tb=9
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Bd5 Nb5+ 45.Kd3 Nc7 46.Bc4 Ke7 47.Ke3 f6 48.Bg8 Ke8 49.Bb3 Ke7 50.Bc4 Kf8 51.Bd3 Nd5+ 
  +-  (1.98)   Depth: 19   00:00:46  33378kN, tb=31
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Kd3 Ke7 45.Ke3 f6 46.Bg8 Ke8 47.Bb3 Ke7 48.Bg8 
  +-  (1.98)   Depth: 20   00:00:58  59073kN, tb=79
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Kd3 Ke7 45.Ke3 f6 46.Bg8 Ke8 47.Bb3 Ke7 
  +-  (1.98)   Depth: 21   00:01:16  111mN, tb=141
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Kd3 Ke7 45.Ke3 f6 46.Bg8 Ke8 47.Bb3 Ke7 48.Bc4 Kf8 49.Kd4 Ke7 50.Kd3 g5 51.Ke3 
  +-  (1.93)   Depth: 22   00:02:16  289mN, tb=401
40.dxc6+ Kd8 41.Be2 h4 42.Bc4 Ke7 43.Kd4 Kf6 44.Kd3 Ke7 45.Ke3 f6 46.Bg8 Kf8 47.Bb3 Nb5 48.Kd3 Nc7 49.Bc4 Kg7 50.Ba2 g5 51.Ke3 Kg6 
  +-  (1.95)   Depth: 23   00:04:07  588mN, tb=2062
40.dxc6+ Kd8 41.g3 Ne6 42.h4 Nc7 43.Be2 Ke7 44.Kd4 Kd8 45.Bc4 Ke7 46.Bd5 f6 47.Bg8 
  +-  (2.31)   Depth: 24   00:14:41  2364mN, tb=6168

(, chessengines20 27.11.2008 )