Engine-assisted game vs Stockfish, move 9 discussion

[MooMoo2]

The most popular move on the move 8 poll was ...a6 with no conditional move. Stockfish played 9. Na3, and the FEN is:
r1bqkb1r/1p3ppp/p1np1n2/4p1B1/4P3/N1N5/PPP2PPP/R2QKB1R b KQkq - 1 9

Game so far: 1.e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Ndb5 d6 7. Bf4 e5 8. Bg5 a6 9. Na3

Depth: 49 ply. Nodes searched: 538,734,199,621 (~539 G)

[richs]

b5 as previously discussed.

[henryzz]

Can people please put forward their arguments for different moves. People need to be able to make a fully informed decision.

[science_man_88]

Originally Posted by henryzz

Can people please put forward their arguments for different moves. People need to be able to make a fully informed decision.

I would but there's 34 moves we can make and about 41 responses they can make in theory so because I'm playing on lichess ( which if I play the computer uses stockfish apparently) and because I suck and haven't stated an opinion for most of the moves there's no basis for me to really comment. there's a lot of illogical moves that can be weeded out because they lose us our queen etc. so that narrows the list but still a lot to consider if you truly want to be fully informed.

[henryzz]

Originally Posted by science_man_88

I would but there's 34 moves we can make and about 41 responses they can make in theory so because I'm playing on lichess ( which if I play the computer uses stockfish apparently) and because I suck and haven't stated an opinion for most of the moves there's no basis for me to really comment. there's a lot of illogical moves that can be weeded out because they lose us our queen etc. so that narrows the list but still a lot to consider if you truly want to be fully informed.

I am not talking about that sort of fully
Each suggested move could do with a paragraph or 2 though. This move could change the game a fair bit.

[gd_barnes]

Originally Posted by science_man_88

I would but there's 34 moves we can make and about 41 responses they can make in theory so because I'm playing on lichess ( which if I play the computer uses stockfish apparently) and because I suck and haven't stated an opinion for most of the moves there's no basis for me to really comment. there's a lot of illogical moves that can be weeded out because they lose us our queen etc. so that narrows the list but still a lot to consider if you truly want to be fully informed.

Really? omg

[LaurV]

As I said, I don't like b5. This move forces him to take that horse in f6 and then we can only beat with the pawn, letting our king naked. b5 Nd5 is not really good for white, because after Be7 he can't exchange on f6 in his favor, he needs to go back (otherwise we exchange on d5 in our favor). So he will not play Nd5 after our b5. And b5 Bxf6, we can not really take it with the queen, because after Nd5 we need to go back to protect Nc7+, and then he has Bxb5! bishop sacrifice for 2 pawns and all our flank is gone (we gave him the horse move to d5 for free!). Best version here I can squeeze from rybka is axb5 Nxb5 Qa5+ c3 and we can not take the horse in b5 because Nd5c7 and we lose the queen. So, after c3, Ra7 Nxa7, we lose the rook. Rb8 is even worse, after b4 we have no place to put the queen, we have to give it for 2 knights. This is very bad for us. Therefore, after 9...b5 10 Bxf6 is the highest probable, and 10...gxf6 is forced, our king is naked.

In spite of the fact that b5 is the most played in the data bases, I will close my move between 9...Be7and 9...Be6, after more analysis following days. 9...Rb8 seems also good, in my opinion.

[WMHalsdorf]

I'm leaning toward 9...Be7 with this as a possible line 10. Bxf6 Bxf6 11. Nc4 Nd4 12. Nd5 b5 13. c3 bxc4 14. cxd4 o-o 15. Bxc4 exd4 16. o-o

[gd_barnes]

I let Stockfish 6 look over night on several consecutive moves. All were > 40 ply. Here is what it came up with:

9...b5
10. Bxf6 gxf6
11. Nd5 f5

I had it on multi-PV mode of 3 meaning that it would show the lines and ranking for the top 3 moves. b5 was > +.1 better than anything else. The 2nd and 3rd best moves were Be7 and Be6 as one might expect.

This combined with the fact that b5 is by far the most played in most databases convinces me that b5 is the best move. Just because our kingside is open doesn't matter IMHO. We will have open lines on his king side with the eventual Rg8 and by eventually moving our king to f8 we will be reasonably well protected.

[gd_barnes]

Originally Posted by WMHalsdorf

I'm leaning toward 9...Be7 with this as a possible line 10. Bxf6 Bxf6 11. Nc4 Nd4 12. Nd5 b5 13. c3 bxc4 14. cxd4 o-o 15. Bxc4 exd4 16. o-o

9...Be7 10. Bxf6 Bxf6 11. Nc4 Nd4 12. Nd5 b5 13. Ncb6 looks bad for us. SF 6 shows an advantage of +.6 to +.7 for white here.

Also I do not think that the immediate swap by white on move 10 is necessarily the best line for it. SF 6 shows that the immediate 10. Nc4 is a strong possibility also. It rates the two possibilities as very close with Nc4 being slightly more likely to be played. Personally I am not fond of allowing the immediate Nc4 by white here.

I think there is a reason why many grandmasters have stuck with 9...b5 here. In the couple of DB's that I have looked at, when 9...Be7 is played here, white wins over half of games and black wins < 20% of games with the remainder being draws. It is quite close with 9...b5 and even 9...Be6 seems to offer black better chances then 9...Be7.

[gd_barnes]

Originally Posted by LaurV

In spite of the fact that b5 is the most played in the data bases, I will close my move between 9...Be7and 9...Be6, after more analysis following days. 9...Rb8 seems also good, in my opinion.

9...Rb8 is not in the opening DB that I am looking at. Once again this allows 10. Nc4. I feel like allowing white to extract the knight so quickly is not in our best interests. We should make him work to extract it.