Move 25 discussion: Everyone vs stockfish

[MooMoo2]

The poll for move 24 just closed, and the most popular move was g3. Stockfish responded with 24...Rc4, and the FEN is:
r5k1/1p3p1p/1p3p2/3R1N2/2r5/6P1/PnP4P/R5K1 w - - 1 25

Game so far: 1.e4 e6 2. d4 d5 3. Nd2 c5 4. Ngf3 Nf6 5. exd5 exd5 6. Bb5+ Bd7 7. Bxd7+ Nbxd7 8. O-O Be7 9. dxc5 Nxc5 10. Nb3 Nce4 11. Nfd4 O-O 12. Nf5 Re8 13. Nxe7+ Rxe7 14. f3 Nd6 15. Bg5 Nc4 16. Bxf6 gxf6 17. Qd4 Qb6 18. Qxb6 axb6 19. Rfd1 Re5 20. f4 Re2 21. Nd4 Re4 22. Nf5 Nxb2 23. Rxd5 Rxf4 24. g3 Rc4

[WMHalsdorf]

25.Rd6 Rxc2 26. Rxb6 Nd3 27.Rxb7 Ne5

[gd_barnes]

I like 25. Nh6+ for a quick draw. Here is a copy-paste of an analysis from the last move:

This is where I have a new idea that could give us a quick draw if SF thinks that he has to worsen his position enough to avoid the draw. I had previously suggested 25. Rd7. I believe it was WMHalsdorf who suggested the improvement 25. Rd6. I'd like to offer up something completely different that could lead to a quick draw:

24. g3 Rc4
25. Nh6+!

Let's look at the possible responses:
25...Kh8 (likely the worst response)
26. Rd7 Rxc2
27. Rxf7 Nc4
28. Rxf6
Even on material and a great position for us here.

25...Kf8
26. Rd7 Kg7
27. Nf5+! Kg6
(We are going for the perpetual check or to worsen black's position instead of immediately trying to gain material.)
28. Nh4+ Kg7 (28...Kg5, Kh5 or Kh6 all lose significant material)
29. Nf5+ Kf8? (black is better to allow the perpetual check with Kg6)
30. Rb1! Na4
(not 30...Rb4? and we win the knight by driving away the rook with 31. c3 Rb5 Nd6)
31. Rbd1 Rc8 or Re4
32. Rxb7
This is a tremendous position for us. We could play for a win. Black would have been better to take the perpetual check at move 29, which I'm sure SF would do.

I think we can rule out those two responses, which leaves us with:

25...Kg7
26. Nf5+ Kf8*
(We have effectively taken 2 moves to bring about the same position with black's king on f8 instead of g8.)
27. Rd7 Rxc2
(I feel like 27. Rd6 gives black too much counterplay after 27...b5.)
28. Nh6 Kg7**
29. Nf5+! Kg6
(Temporarily down 2 pawns but consistent to the end! If Kf8 or Kg8, we just repeat ourselves with Nh6 aiming for 3-time repetition.)
30. Nh4+ Kg7
(Any other move by black loses material with 31. Rxf7 and eventually Rf1 as we threaten multiple pawns, perpetual check, or 3-time repetition.)
31. Nf5+
(With perpetual check or 3-time repetition in a few moves.)

*Another possibility for black's move 26:
26...Kh8
27. Rd7 Rxc2
28. Rxf7 Nc4
29. Rxb7 Nd2 threatening Nf3+ and preventing Rf1
30. Nh4
Black can choose to swap off his b6 pawn for our b2 pawn but besides that no progress can be made.

**Another possibility for black's move 28:
28...Ke8
29. Rxf7 Nd3
30. Rxh7 Raxa2
31. Rxa2 Rxa2
32. Rxb7
Dead drawn here.

[LaurV]

I have a problem with this game...
Due to all those discussions in the "puzzle" thread, I installed the newest SF linked by Serge, and played with it. Of course, you guessed, I could not restrain myself, and I ended up putting this current position into SF and giving it a run.

Now, I will not spoil the thread, telling if we played well or not, neither if, according with SF, it is a draw or not. I think the best choice is that I won't suggest any move for a while, and also not vote.

But I will watch close!

Sorry for that.

[gd_barnes]

Originally Posted by WMHalsdorf

25.Rd6 Rxc2 26. Rxb6 Nd3 27.Rxb7 Ne5

TL;DR note: See the bolded line below.

Let's take a close look at 25. Rd6.

In your line, I think that black has a better 26th move. There is a variation in that line where I don't feel like we are so good:

25. Rd6 Rxc2 26. Rxb6 Nc4 27. Rxb7 Nd2!

I think we have three choices here, all of which leave us a pawn down with not great compensation:
28. Nd4 Rcxa2
29. Rxa2 Rxa2
30. Rb8+ Kg7
31. Nf5+ Kg6
32. Nh4+ Kh5
(A pawn down and probably drawn but we have to fight for it)

28. Nh4
(Frees up the a8 rook; black can either win the a2 pawn right away and swap off rooks or simply move Ra3 or something similar to begin building an attack. Our knight is stuck on the side and I feel like we are sitting ducks.)

28. Nh6+ Kh8! (This surprising move into the corner actually gives us difficulty.)
29. Nxf7+ Kg7
30. Ne5+ Kg8
31. Ng4 Nf3+
32. Kf1 Nxh2+
33. Nxh2 Rxh2
34. Kg1 Rhxa2
35. Rxa2 Rxa2
(Here it's rook-one pawn vs. rook-two pawns. We can probably draw but it's more difficult than we want to try against SF.)

So from the original position after 25. Rd6, I think we need to back up first one move and then two moves and see if we can do better:

Backing up one move (meaning changing our move 27), I think the only other reasonable move is 27. Nh6+ so we have:
25. Rd6 Rxc2
26. Rxb6 Nc4
27. Nh6+ Kf8*
28. Rxb7 Ne5
(good for us but...)

*I feel like black can also play 27...Kg7 or Kh8 here. Kg7 is more drawish so I feel like SF might try 27...Kh8 here aiming for tactical lines that are relatively similar to the one that I showed above. I feel like the lines are too difficult and numerous to attempt to analyze. Regardless, I'd rather not get into a tactical battle with SF.

Backing up two moves (meaning changing our move 26), I once again feel like our only reasonable response is 26. Nh6+. Other tries: I don't care for 26. Rxf6 because it frees up black's a8 rook. I also don't care for 26. Re1 because it allows Nc4 and forces us to take the f-pawn, also removing the mate threat. Some analysis:

25. Rd6 Rxc2
26. Nh6+ Kg7*
27. Nf5+ Kg6
28. Nh4+ Kg5
29. Rf1!

*It does not appear that 26...Kf8 or Kh8 are any better for black. They avoid this "drawing attack" by us but put black in a tough spot.

So...this line looks pretty good for us. Therefore I think that 25. Rd6 is good. I just don't think that beginning to pick off pawns on move 26 would be a good follow up response.

Conclusion:
I cannot argue with the merit of 25. Rd6. It looks good but...in most lines it looks like we want to attempt to degrade black's position with Nh6+ by forcing him to accept a 3-time repetition or a perpetual check or by forcing him to move his king to a less favorable position. So I cannot see a reason for us to play 25. Rd6 (or Rd7) before Nh6+. We should wait to see what he does with his king after a check or two before deciding what to do with our rook. In many variations after black moves his king a time or two, we can play Rf1! instead of wasting our time picking off pawns. Such a move could well put us in an excellent position for a drawing attack on the king-side of the board.

[gd_barnes]

Originally Posted by LaurV

I have a problem with this game...
Due to all those discussions in the "puzzle" thread, I installed the newest SF linked by Serge, and played with it. Of course, you guessed, I could not restrain myself, and I ended up putting this current position into SF and giving it a run.

Now, I will not spoil the thread, telling if we played well or not, neither if, according with SF, it is a draw or not. I think the best choice is that I won't suggest any move for a while, and also not vote.

But I will watch close!

Sorry for that.

I can understand that. We will miss your analysis. It is for that exact reason that I have not downloaded SF. The temptation would be too great. It must be a great program and I look forward to downloading it after we finish both variations of this game.

I very much enjoy pushing pieces around for hours at a time. I played correspondence chess extensively back when we mailed moves in the 80s but got burned out. This game has reminded me of why I enjoyed it so much. I like it a lot more than over-the-board chess because I was always in time trouble there.

LaurV, I'll miss your analysis and commentary also. (You may wish to check yourself into `computer chess rehab.` to resist any such future temptation. There may be a 12 step program involved ...)

[WMHalsdorf]

Originally Posted by gd_barnes

TL;DR note: See the bolded line below.

Let's take a close look at 25. Rd6.

In your line, I think that black has a better 26th move. There is a variation in that line where I don't feel like we are so good:

25. Rd6 Rxc2 26. Rxb6 Nc4 27. Rxb7 Nd2!

I think we have three choices here, all of which leave us a pawn down with not great compensation:
28. Nd4 Rcxa2
29. Rxa2 Rxa2
30. Rb8+ Kg7
31. Nf5+ Kg6
32. Nh4+ Kh5
(A pawn down and probably drawn but we have to fight for it)

28. Nh4
(Frees up the a8 rook; black can either win the a2 pawn right away and swap off rooks or simply move Ra3 or something similar to begin building an attack. Our knight is stuck on the side and I feel like we are sitting ducks.)

28. Nh6+ Kh8! (This surprising move into the corner actually gives us difficulty.)
29. Nxf7+ Kg7
30. Ne5+ Kg8
31. Ng4 Nf3+
32. Kf1 Nxh2+
33. Nxh2 Rxh2
34. Kg1 Rhxa2
35. Rxa2 Rxa2
(Here it's rook-one pawn vs. rook-two pawns. We can probably draw but it's more difficult than we want to try against SF.)

So from the original position after 25. Rd6, I think we need to back up first one move and then two moves and see if we can do better:

Backing up one move (meaning changing our move 27), I think the only other reasonable move is 27. Nh6+ so we have:
25. Rd6 Rxc2
26. Rxb6 Nc4
27. Nh6+ Kf8*
28. Rxb7 Ne5
(good for us but...)

*I feel like black can also play 27...Kg7 or Kh8 here. Kg7 is more drawish so I feel like SF might try 27...Kh8 here aiming for tactical lines that are relatively similar to the one that I showed above. I feel like the lines are too difficult and numerous to attempt to analyze. Regardless, I'd rather not get into a tactical battle with SF.

Backing up two moves (meaning changing our move 26), I once again feel like our only reasonable response is 26. Nh6+. Other tries: I don't care for 26. Rxf6 because it frees up black's a8 rook. I also don't care for 26. Re1 because it allows Nc4 and forces us to take the f-pawn, also removing the mate threat. Some analysis:

25. Rd6 Rxc2
26. Nh6+ Kg7*
27. Nf5+ Kg6
28. Nh4+ Kg5
29. Rf1!

*It does not appear that 26...Kf8 or Kh8 are any better for black. They avoid this "drawing attack" by us but put black in a tough spot.

So...this line looks pretty good for us. Therefore I think that 25. Rd6 is good. I just don't think that beginning to pick off pawns on move 26 would be a good follow up response.

Conclusion:
I cannot argue with the merit of 25. Rd6. It looks good but...in most lines it looks like we want to attempt to degrade black's position with Nh6+ by forcing him to accept a 3-time repetition or a perpetual check or by forcing him to move his king to a less favorable position. So I cannot see a reason for us to play 25. Rd6 (or Rd7) before Nh6+. We should wait to see what he does with his king after a check or two before deciding what to do with our rook. In many variations after black moves his king a time or two, we can play Rf1! instead of wasting our time picking off pawns. Such a move could well put us in an excellent position for a drawing attack on the king-side of the board.

I had not considered Nh6+ thinking that it didn't really looked like it would lead to anything.

[gd_barnes]

Any more opinions here?

There's 25. Nh6+ or Rd6 so far.

[The Carnivore]

Originally Posted by gd_barnes

Any more opinions here?

There's 25. Nh6+ or Rd6 so far.

Nd4 was mentioned here:
http://www.mersenneforum.org/showpos...2&postcount=25
http://www.mersenneforum.org/showpos...8&postcount=27

[gd_barnes]

Originally Posted by The Carnivore

Nd4 was mentioned here:
http://www.mersenneforum.org/showpos...2&postcount=25
http://www.mersenneforum.org/showpos...8&postcount=27

25. Nd4 would be backtracking. The question being, why would we have previously moved Nf5 and sacrificed a pawn only to move back a few moves later.