OpenChess

Or is it Qa8 or b3?

3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 18

Hi Swami!

I'd say, Rxa2 is a clear best move.

After very short variants only,

[Event "bm?"]
[Site "Dort"]
[Date "2010.09.13"]
[Round "1"]
[White "Swami"]
[Black "Me"]
[Result "*"]
[Annotator "Martan,Peter"]
[SetUp "1"]
[FEN "3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 1"]
[PlyCount "9"]
[TimeControl "40/2400:20/1200:1800"]

1... Rxa2 (1... Qa8 $6 2. Nc1 Nc5 3. Qd5 Qxd5 4. exd5 b3 5. axb3) (1... b3 $2
2. axb3 Rxe4 3. f6 gxf6 4. Ng3) 2. Kxa2 Qa8+ 3. Kb3 Bxg5 4. Qd3 Nef6 5. Bg2
Bxe3 *

I think Rxa2 is the only move to get full compensation if not even advantage for Black,

Peter wrote:
1... Rxa2 (1... Qa8 $6 2. Nc1 Nc5 3. Qd5 Qxd5 4. exd5 b3 5. axb3) (1... b3 $2
2. axb3 Rxe4 3. f6 gxf6 4. Ng3) 2. Kxa2 Qa8+ 3. Kb3 Bxg5 4. Qd3 Nef6 5. Bg2
Bxe3 *

I think Rxa2 is the only move to get full compensation if not even advantage for Black,

...but after going on a little further into the main variant above, there's a little doubt about Black's compensation again:

[Event "PCWINXP, 120'/40+60'/20+30'"]
[Site "Dort"]
[Date "2010.09.13"]
[Round "1"]
[White "Deep Shredder 12 UCI"]
[Black "Deep Rybka 4 w32"]
[Result "*"]
[SetUp "1"]
[FEN "3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 1"]
[PlyCount "24"]

1... Rxa2 2. Kxa2 Qa8+ 3. Kb3 Bxg5 4. Qd3 Nef6 5. Bg2 Bxe3 6. Qxe3 Qc6 7. Ra1
Nxe4 (7... Nc5+ 8. Ka2 Ng4 9. Qf3 Nf2 10. Kb1 Ncxe4 11. Qe3 Qd5 12. Bxe4 Nxe4
13. b3) 8. Bxe4 Nc5+ 9. Ka2 b3+ 10. Kb1 Nxe4 11. Rc1 Nd2+ 12. Qxd2 Qe4+ 13. Rc2

Peter wrote:

Peter wrote:
1... Rxa2 (1... Qa8 $6 2. Nc1 Nc5 3. Qd5 Qxd5 4. exd5 b3 5. axb3) (1... b3 $2
2. axb3 Rxe4 3. f6 gxf6 4. Ng3) 2. Kxa2 Qa8+ 3. Kb3 Bxg5 4. Qd3 Nef6 5. Bg2
Bxe3 *

I think Rxa2 is the only move to get full compensation if not even advantage for Black,

...but after going on a little further into the main variant above, there's a little doubt about Black's compensation again:

[Event "PCWINXP, 120'/40+60'/20+30'"]
[Site "Dort"]
[Date "2010.09.13"]
[Round "1"]
[White "Deep Shredder 12 UCI"]
[Black "Deep Rybka 4 w32"]
[Result "*"]
[SetUp "1"]
[FEN "3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 1"]
[PlyCount "24"]

1... Rxa2 2. Kxa2 Qa8+ 3. Kb3 Bxg5 4. Qd3 Nef6 5. Bg2 Bxe3 6. Qxe3 Qc6 7. Ra1
Nxe4 (7... Nc5+ 8. Ka2 Ng4 9. Qf3 Nf2 10. Kb1 Ncxe4 11. Qe3 Qd5 12. Bxe4 Nxe4
13. b3) 8. Bxe4 Nc5+ 9. Ka2 b3+ 10. Kb1 Nxe4 11. Rc1 Nd2+ 12. Qxd2 Qe4+ 13. Rc2

They are arguing this in CCC. IMO Rxa2! is best and gains the initiative.

Swaminathan wrote:Or is it Qa8 or b3?

3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 18

Qa8.

Best,
Gerold.

Hi again!

As I said at CCC I'm not quite sure about it anymore neither.
As well as after 1... Qa8 White's chances after 1... Rxa2 to me seem to remain better as well as with both moves the game isn't won for any side as far as I can see.

[Event "bm?"]
[Site "Dort"]
[Date "2010.09.13"]
[Round "1"]
[White "Swami"]
[Black "STS"]
[Result "*"]
[Annotator "Martan,Peter"]
[SetUp "1"]
[FEN "3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 1"]
[PlyCount "24"]
[TimeControl "40/2400:20/1200:1800"]

1... Rxa2 (1... Qa8 2. Nc1 Nc5 3. Qd5 Qxd5 4. exd5 b3 5. Nxb3 (5. h4 f6 6. axb3
Re4 7. Rh3 fxg5 8. hxg5 Rxe3 9. Rxe3 Bxg5 10. Rc3 Nf6 11. b4 Nce4 12. Rc6) (5.
axb3 Re4) 5... Nxb3 6. axb3 Rg4 7. Rd3 Nc7 8. Be2 Rh4 9. Bb6 Na8 10. Bf2 Re4
11. Bf3 Rf4 12. Bg3) (1... b3 $2 2. axb3 Rxe4 3. f6 gxf6 4. Ng3) 2. Kxa2 Qa8+
3. Kb3 (3. Kb1 Qxe4+ 4. Qd3 Qxh1) 3... Bxg5 4. Qd3 Nef6 5. Bg2 (5. Ng3 Bxe3 6.
Qxe3 Rc8) 5... Bxe3 6. Qxe3 Qc6 7. Ra1 Nxe4 (7... Nc5+ 8. Ka2 Ng4 9. Qf3 Nf2
10. Kb1 Ncxe4 11. Qe3 Qd5 12. Bxe4 Nxe4 13. b3) 8. Bxe4 Nc5+ 9. Ka2 b3+ 10. Kb1
Nxe4 11. Rc1 Nd2+ 12. Qxd2 Qe4+ 13. Rc2 *

Still I'd prefer 1... Rxa2 for it's initiative and simply because it's more beautiful but I wouldn't call it a clear best move any longer, so it doesn't seem as good as a best move problem as it did at first glance to me.
Very nice prob anyhow, thanks for it.

Gerold wrote:

Swaminathan wrote:Or is it Qa8 or b3?

3qnrk1/3nbppp/3p4/4pPP1/rp2P3/4B3/PP1QN2P/1K1R1B1R b - - 0 18

Qa8.

Best,
Gerold.

Nope..

Peter wrote: Still I'd prefer 1... Rxa2 for it's initiative and simply because it's more beautiful ...

And now I really have to be ashamed, not having noticed how well known and disputed this position is alredy in theory.
Most modern engine books have many variants up to 30 and more moves, Hiarcs13cBook.ctg seems to be the completest to me but also in R3.ctg and DeepFritz11.ctg it was well known.
Even if in most books after the tournament move 18... Rxa2 (Qa8 is in all the books, I've looked for it, blocked and not to be played actively) 19. Kc1 is favored before Kxa2 (again blocked in most cases), I don't think this one to be the best one, as in my variants before I don't see White's chances as good as with the acceptation of the sac at once.
The game from master tournaments that matches farest with my analysis, I found this one: 0-1, Szelag Marcin (POL) - Bobras Piotr (POL), Ustron (Poland), 2007 :

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 e5 7. Nb3 Be7 8. f3 O-O 9. Qd2 Be6 10. O-O-O Nbd7 11. g4 b5 12. g5 b4 13. Ne2 Ne8 14. f4 a5 15. f5 Bxb3 16. cxb3 a4 17. bxa4 Rxa4 18. Kb1 Rxa2 19. Kxa2 Qa8+ 20. Kb3 Bxg5 21. Qd3 Nef6 22. Bg2 Bxe3 23. Qxe3 Qc6 24. Rc1 Nc5 25. Rxc5 dxc5 26. Ra1 c4 27. Kc2 Ng4 28. Qg3 Rd8 29. Qxg4 Qd6 30. Nd4 Qxd4 31. Rd1 b3 32. Kc1 Qe3 33. Kb1 Rd2 34. Qf3 Qa7 35. Qe2 Qa2 36. Kc1 Qxb2

According to my analysis and most engine- books 24. Rc1 is not as strong as Ra1, here is the main variant following this move from Hiarcs13cBook.ctg to its end:

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 e5 7. Nb3 Be7 8. f3
O-O 9. Qd2 Be6 10. O-O-O Nbd7 11. g4 b5 12. g5 b4 13. Ne2 Ne8 14. f4 a5 15. f5
Bxb3 16. cxb3 a4 17. bxa4 Rxa4 18. Kb1 Rxa2 19. Kxa2 Qa8+ 20. Kb3 Bxg5 21. Qd3
Nef6 22. Bg2 Bxe3 23. Qxe3 Qc6 24. Ra1 Nxe4 25. Bxe4 Nc5+ 26. Ka2 b3+ 27. Kb1
Nxe4 28. Rc1 Nd2+ 29. Qxd2 Qe4+ 30. Rc2 Rc8 31. Nc3 Qxf5 32. Ra3 bxc2+ 33. Qxc2
Qf1+ 34. Nd1 Rd8 35. Ka2 Qf6
3r2k1/5ppp/3p1q2/4p3/8/R7/KPQ4P/3N4 w - - 0 36