Testposition

[bob]

These "brilliant moves" are often the result of a "not-brilliant reply".

I think that if black just avoids taking the rook, this is not so brilliant after all...

[MikeGL]

These "brilliant moves" are often the result of a "not-brilliant reply".

I think that if black just avoids taking the rook, this is not so brilliant after all...

Who said programmers don't have a sense of humor.

Maybe some human psychology was involved, Kasparov will be called a
coward if he avoids the offer. A lot of great champions accepting gambits
just to prove the gambit is unsound. Even Fischer in a world
championship lost a game by capturing the h2 pawn of Spassky resulting
to Fischers D.S.Bishop being trapped and bobby lost the game.


Regarding the above position, the intuition of Lyudmil was reached by
an engine at depth 27, but the move 27...g6 is more logical positionally compared to Lyudmil's 27...g5, i think, due
to king safety issues (considering all heavy pieces are still on the board)
and avoiding a hemmed in B at f8. So g6 seems more accurate than
27... g5. I am sure there is an eval penalty in stockfish if pawns are placed on the same color as the remaining lone B.

[MikeGL]

In the g5 line, SF is very much afraid of a line ending here:

[d]8/2r2pk1/P7/1B2pK2/3bP3/6P1/R7/8 w - - 0 31

150cps white edge, why on earth should SF choose this line?

As the white king and rook get more active, the advantage increases, but no much benefit from this.

Maybe the fact that on g5 white has only acceptable response, Bc7, should somehow ring a bell.

I tried to continue the game and white is winning due to extra outside pawn. But it requires further analysis if the line is correct.

[pgn]
[Event "Talkchess"]
[Site "Talkchess"]
[Date "2015.06.06"]
[Round "?"]
[White "Postmortem_Anand"]
[Black "Postmortem_Kasparov"]
[Result "*"]
[BlackElo "2400"]
[Time "20:08:13"]
[WhiteElo "2400"]
[TimeControl "600"]
[SetUp "1"]
[FEN "8/2r2pk1/P7/1B2pK2/3bP3/6P1/R7/8 w - - 0 31"]
[Termination "unterminated"]
[PlyCount "36"]
[WhiteType "human"]
[BlackType "human"]

31. Ba4 Rc1 32. Bb3 Rf1+ 33. Kg4 Ba7 34. Bd5 Rf6 35. Bb7 Kf8 36. Rc2 Ke7
37. Rc8 Rg6+ 38. Kf3 Rf6+ 39. Kg2 Rf2+ 40. Kh3 Kd7 41. Ra8 Bd4 42. Bd5 Kc7
43. Rf8 Bc5 44. Rxf7+ Rxf7 45. Bxf7 Kb6 46. Kg4 Bf2 47. Bc4 Kc7 48. Kf3 1-0
[/pgn]

After 48.Kf3 white is ahead +8 point something and climbing.

[Lyudmil Tsvetkov]

It seems the puzzle is an "avoid move", for 27... Nxd5

So the correct fen line could be:
r3rbk1/1p3ppp/1B2qn2/PQ1Rp3/2P1P3/5B1P/6P1/1R5K b 1 1 am Nxd5;

[d]r3rbk1/1p3ppp/1B2qn2/PQ1Rp3/2P1P3/5B1P/6P1/1R5K b 1 1

Stockfish 6 actually avoids 27... Nxd5 at Depth 27, and prefers 27...g6 or 27... h5 at -22 centipawns.

g6 does not help, probably h5 is no good too, in any case weaker than g5.

g6 is met by c5, which SF does not see, and white is winning.

black should act very quickly, otherwise the threat c5 remains.

[Lyudmil Tsvetkov]

In the g5 line, SF is very much afraid of a line ending here:

[d]8/2r2pk1/P7/1B2pK2/3bP3/6P1/R7/8 w - - 0 31

150cps white edge, why on earth should SF choose this line?

As the white king and rook get more active, the advantage increases, but no much benefit from this.

Maybe the fact that on g5 white has only acceptable response, Bc7, should somehow ring a bell.

I tried to continue the game and white is winning due to extra outside pawn. But it requires further analysis if the line is correct.

[pgn]
[Event "Talkchess"]
[Site "Talkchess"]
[Date "2015.06.06"]
[Round "?"]
[White "Postmortem_Anand"]
[Black "Postmortem_Kasparov"]
[Result "*"]
[BlackElo "2400"]
[Time "20:08:13"]
[WhiteElo "2400"]
[TimeControl "600"]
[SetUp "1"]
[FEN "8/2r2pk1/P7/1B2pK2/3bP3/6P1/R7/8 w - - 0 31"]
[Termination "unterminated"]
[PlyCount "36"]
[WhiteType "human"]
[BlackType "human"]

31. Ba4 Rc1 32. Bb3 Rf1+ 33. Kg4 Ba7 34. Bd5 Rf6 35. Bb7 Kf8 36. Rc2 Ke7
37. Rc8 Rg6+ 38. Kf3 Rf6+ 39. Kg2 Rf2+ 40. Kh3 Kd7 41. Ra8 Bd4 42. Bd5 Kc7
43. Rf8 Bc5 44. Rxf7+ Rxf7 45. Bxf7 Kb6 46. Kg4 Bf2 47. Bc4 Kc7 48. Kf3 1-0
[/pgn]

After 48.Kf3 white is ahead +8 point something and climbing.

those are 20 moves/40 plies.

and who played those moves?

certainly the ending is a draw - too few material, opposite coloured bishops

[Lyudmil Tsvetkov]

In the g5 line, SF is very much afraid of a line ending here

Can you give this whole line? Thanks in advance.

whole line is obvious: Rd5? (c5! wins) g5 Bc7 (simply no other moves, therefore g5 is good) Nd5 cd5 Qa6 Qb7 Qb7 Rb7 Re7

[d]r4bk1/1RB1rp1p/8/P2Pp1p1/4P3/5B1P/6P1/7K w - - 0 6

and now try to win this with white

[acase]

Hi Lyudmil,


Here is what Stockfish (the latest development version) says after your 27...g5 move with a couple of hours of looking at the position, and looks like the ending position is just as you called it...a draw.


New game
r3rbk1/1p3p1p/1B2qn2/PQ1Rp1p1/2P1P3/5B1P/6P1/1R5K w - - 0 1

Analysis by Stockfish 050615 64 POPCNT:


28.Bc7 Nxd5 29.cxd5 Qa6 30.Qxb7 Qxb7 31.Rxb7 Re7 32.d6 Rd7 33.Rb6 Rc8 34.Kh2 Rcxc7 35.dxc7 Rxc7 36.a6 Bc5 37.Rb7 Rxb7 38.axb7 Bd6 39.h4 gxh4 40.Kh3 Kg7 41.Kxh4 Kg6 42.Bg4 Be7+ 43.Kg3 Bd6 44.Bf5+ Kh6 45.Kh4 Bb8 46.Kg4 Bc7 47.g3 Bd6 48.Kh4 Bb8 49.Bg4 Kg6 50.Bd7 Bd6 51.Bf5+ Kh6 52.g4 f6 53.Be6 Kg6 54.Bc4 Kh6 55.Bb3 Kg6 56.Bd5 Bc7 57.Bg8 Bb8 58.Bd5 Bd6
+/- (0.81) Depth: 49/74 02:27:47 46354MN, tb=3908988



here is the position after all of the above moves are played:

[d]8/1P5p/3b1pk1/3Bp3/4P1PK/8/8/8 w - - 0 59

[syzygy]

In the g5 line, SF is very much afraid of a line ending here:

[d]8/2r2pk1/P7/1B2pK2/3bP3/6P1/R7/8 w - - 0 31

150cps white edge, why on earth should SF choose this line?

As the white king and rook get more active, the advantage increases, but no much benefit from this.

Maybe the fact that on g5 white has only acceptable response, Bc7, should somehow ring a bell.

Ra4 seems to win here:

Code: Select all

info depth 46 seldepth 70 multipv 1 score cp 511 nodes 8812113811 nps 13491384 hashfull 999 tbhits 32712853 time 653166 pv a2a4 c7c8 a4c4 c8b8 b5c6 d4e3 c6d5 b8b1 c4c7 b1f1 f5e5 f1a1 c7f7 g7g6 f7f3 e3g1 d5c4 a1a4 e5d5 a4a5 d5e6 a5a4 c4d3 g6g5 f3f7 a4a3 d3c4 a3a4 f7g7 g5h6 g7c7 a4a5 c7f7 a5a4 c4d3 a4a3 d3b5 h6g5 e4e5 a3a1 f7g7 g5h6 e6f6 a1a3 g7b7 a3f3 f6e6 h6g5 e6d5 f3f8 d5e4 f8d8

At depth 47 the score is +7.42 now and keeps climbing.
It just resolved to +8.82:

Code: Select all

info depth 47 seldepth 77 multipv 1 score cp 882 nodes 13365921658 nps 13649113 hashfull 999 tbhits 54915966 time 979252 pv a2a4 c7c8 a4c4 c8b8 b5c6 d4e3 c6d5 b8b6 c4c6 b6b1 c6c7 b1f1 f5e5 f1a1 c7f7 g7g6 f7f3 e3g1 d5c4 a1a4 e5d5 a4a5 d5e6 a5a4 c4d3 g6g5 e4e5 g5g4 f3f7 g1e3 d3b5 a4a1 b5c4 g4h3 e6d6 a1d1 d6c6 d1c1 c6d5 h3h2 e5e6 c1d1 d5c6 d1d4 e6e7 d4c4 c6d6 c4a4 e7e8q a4a6 d6d5 a6a3 e8h8 h2g1 h8h3 a3a5 d5e4

Depths 48 and 49:

Code: Select all

info depth 48 seldepth 77 multipv 1 score cp 857 nodes 15661735979 nps 13622620 hashfull 999 tbhits 65067155 time 1149686 pv a2a4 c7c8 a4c4 c8h8 c4c7 d4b6 c7b7 b6e3 b5c4 h8h5 f5g4 h5h1 b7f7 g7g6 f7c7 h1g1 c7c6 g6h7 c4d5 g1a1 g4f5 e3d4 f5g5 d4e3 g5f6 a1f1 f6e5 f1a1 c6c7 h7g6 d5c4 g6g5 e5d6 g5g4 e4e5 a1d1 c4d5 d1a1 c7g7 g4f5 g7f7 f5g6 d5c4 a1d1 d6e6 d1d8 f7c7 e3b6 c7b7 d8e8 e6d6 e8d8 d6e7 b6a5 b7b5 a5c7 b5c5 d8e8 e7e8 c7b8 e5e6 b8a7

Code: Select all

info depth 49 seldepth 78 multipv 1 score cp 979 nodes 18545141867 nps 13510053 hashfull 999 tbhits 76196621 time 1372692 pv a2a4 c7c8 a4c4 c8h8 c4c7 d4b6 c7b7 b6d4 b5c4 h8h5 f5g4 h5h1 b7f7 g7g6 f7c7 g6f6 c4a2 h1a1 c7c2 a1e1 c2c6 f6g7 g4g5 d4e3 g5f5 e1f1 f5e5 f1a1 c6c7 g7h6 a2c4 a1a5 e5e6 e3g1 c7f7 a5a4 f7f1 g1d4 e4e5 d4e3 f1f6 h6g5 f6f3 e3c1 e6d5 a4a5 d5c6 g5g4 f3f7 a5a4 c4d3 a4a3 d3e2 g4h3 e5e6 a3c3 c6d5 c3g3 e6e7 g3g8 e2b5 g8g5 d5c6 g5g8 a6a7 c1g5 f7f8

[syzygy]

And depth 50:

Code: Select all

info depth 50 seldepth 84 multipv 1 score cp 1212 nodes 26849254377 nps 13356369 hashfull 999 tbhits 113073954 time 2010221 pv a2a4 c7c8 a4c4 c8g8 c4c7 g7h6 c7c6 h6g7 b5c4 g8h8 c6c7 h8h5 f5g4 h5h1 c4f7 g7f6 f7a2 h1a1 c7c2 a1e1 c2c6 f6g7 g4g5 d4e3 g5f5 e1f1 f5e5 f1a1 c6c7 g7g6 a2c4 a1a5 e5e6 g6g5 c7g7 g5h6 g7f7 a5a4 e6d5 a4a5 d5d6 e3c5 d6e6 a5a3 e4e5 a3g3 e6d5 c5g1 f7c7 g3f3 d5d6 g1e3 a6a7 f3f8 c4d5 f8d8 d6e6 d8e8 e6f5 e8f8 f5e4 e3g5 a7a8q f8f4 e4d3 h6h5 a8e8 h5g4 e8g6 f4f2 c7c4 f2f4

Possibly more interesting is why Rc4 cannot be countered by Rxc4:
[d]8/5pk1/P7/1B2pK2/2rbP3/6P1/8/8 w - -

Code: Select all

info depth 36 seldepth 48 multipv 1 score cp 12337 nodes 48086855 nps 10533812 hashfull 31 tbhits 496524 time 4565 pv b5c4 f7f6 g3g4 d4f2 c4d5 f2d4 d5e6 d4e3 g4g5 e3a7 e6d5 f6g5 f5e5 a7c5 d5e6 g7f8 e5d5 c5a7 e6f5 f8f7 e4e5 a7e3 d5d6 f7e8 d6c6 e3g1 c6b7 e8f8 a6a7 f8f7 a7a8q f7g7 b7c6 g1d4 a8b7 g7g8 b7c8 g8g7

TB win.
Higher depths find faster routes to TB wins:

Code: Select all

info depth 60 seldepth 64 multipv 1 score cp 12342 nodes 1286507664 nps 21173595 hashfull 317 tbhits 7935039 time 60760 pv b5c4 f7f6 g3g4 d4f2 c4d5 f2d4 d5e6 g7f8 f5f6 d4b6 e6f7 b6d8 f6e5 d8b6 e5e6 b6a7 e4e5 f8g7 e6d7 g7h6 g4g5 h6g7 e5e6 g7h7 e6e7 a7e3 e7e8q e3g5

Code: Select all

info depth 68 seldepth 64 multipv 1 score cp 12343 nodes 6848062405 nps 22382507 hashfull 928 tbhits 36522466 time 305956 pv b5c4 f7f6 g3g4 d4f2 c4d5 f2d4 d5e6 g7f8 f5f6 d4b6 e6f7 b6c5 g4g5 c5e7 f6e5 e7c5 e5d5 c5f2 e4e5 f2a7 e5e6 f8e7 g5g6 e7f8 g6g7 f8g7

[gordonr]

whole line is obvious: Rd5? (c5! wins) g5 Bc7 (simply no other moves, therefore g5 is good)

I'm not convinved it is obvious. Instead of Bc7 there is another candidate move: Rd3. I don't claim White wins but White has the better chances.

I've also seen the other posts doubting the draw after Bc7.