Sunday, July 06, 2014

Eagle eyes tactic



White to move. What is the best continuation for White?

4q1k1/1b1nr1b1/p1pr1np1/1p1p2B1/1P1P3Q/1NP3N1/6P1/RB3RK1 w - - 0 1

11 comments:

Tim Callinan said...

Bishop on b7 unprotected and Rd6 unprotected but its the N on d7 that will become exchanged and make the pin on f6 too much for black. So 1. Nc5! Bc8 2. Nxd7 Bxd7 3. Bxf6 Bxf6 4. Rxf6 Rxf6 5. Qxf6 winning the piece Another try is 1.Nc5 Nf8 2. Nxb7 Rxb7 3. Bxf6 Bxf6 4. Rxf6 Rxf6 5. Qxf6 losing the knight again. If the knight ever tries to move on f6 the rook will be taken on e7.

Yancey Ward said...

Nc5 jumps out at me at first as a way to undermine the defense of the f6 knight who is attacked triply and defended triply. With Nc5 white is attacking the undefended bishop at b7 who must be moved, protected, or the knight must be captured. Let's look at the latter idea first:

1. Nc5 Nc5
2. bc5

Does it matter with which pawn white captures? I can't really be sure which is best, but my preference bc5 for no real reason. Continuing:

2. .....Rde6
3. Bf6

Now the knight is protected inadequately:

3. .....Bf6
4. Rf6 Rf6
5. Qf6 and white has won a piece and is up a piece for a pawn.

Now, at move 1, can black do better by retreating the bishop?

1. Nc5 Bc8
2. Nd7 Red7
3. Bf6

Looks like it wins a piece, but what if black plays....

3. .....Qe3

Now white seems to have a problem. He can't play Kh2 or Kh1:

4. Kh2? Bf6!
5. Rf6 Rf6
6. Qf6 Rh7 and white is going to get himself mated. So, at move 4, white must block the check and leave his rook pinned:

4. Rf2 Bf6
5. Qg4 Qg5 (Bg5 better or not?)

And black is clearly better here, though I doubt the edge is decisive.

Now, after

1. Nc5 Bc8

I do now notice that the rook at d6 is terribly restrained- what about...

2. Bf4 Rde6
3. Ne6 Re6

Wins the exchange for white, at least, and white still has some pressure on the black position.

Anonymous said...

No idea.

flyingcod said...

Kf5?

Anonymous said...

1 Nc5

Lenny Cavallaro said...

1) Nc5 appears to win.

1) Nc5 (attacks the Bishop -- loose end): if Nxc5
2) bxc5, R moves, and Bxf6 should win a piece.

1) . . . Ba8 doesn't help, since 2) Nxd7 still leaves White ahead a piece -- or a Rook if 2) . . . Nxd7.

Lenny Cavallaro said...

Nc5 should work.

1) Nc5 (attacks the Bishop -- loose end): if Nxc5
2) bxc5, R moves, and Bxf6 wins a piece.

1) . . . Ba8 doesn't help, since 2) Nxd7 still leaves White ahead a piece -- or a Rook if 2) . . . Nxd7.

Papan Catur said...

Candidates move are :

a. 1.Bxf6 (take material) but ...Bxf6 2. Qf4 Rde6 nothing for white
b. 1.Rxf6 (take material) but ...Bxf6 2.Bxf6 Rxf6 nothing for white
c. 1.Nc5 (attacking bishop on b7) if 1... Nxc5 2. dxc5 Rde6 3.Bxf6 Rxf6 4. Rxf6 Bxf6 5. Qxf6 white wins.
d. 1.Bf5 (attacking knight on d7 if ...gxf5 2. Nxf5 (fork) Rde6 3.Nc5 Nxc5 4. bxc5 Re4 5. Nxe7+ Qxe7 6.
Bxf6 Rxh4 7.Bxe7 white winning the exchange

Anonymous said...

1.Nc5! seems the best bet. 1. Bxg6 appears good but is complicated and BQ gets a vantage point in g6.

>A-1..Nxc5.2.bxc5.Re6.3.Bxf6.Bxf6. 4.Rxf6.Rxf6.5.Qxf6 wins a piece... Qe1+.6.Kh2.Qxc3.7.Bxg6! mates.
If 3...Re1.4.Bxe7.and white is R up.

>B-1..Re1.2.Nxb7 winning a piece.. Rxf1+.3.Nxf1!.Re6.4.Nc5! winning easily

>C-1...Bc8.2.Nxd7.B/Q/Rxd7.3.Bxf6 winning a piece. If 2...Nxd7. 3.Bxe7 winning a full Rook.

The key is that the Nf6 is pinned against a Re7 which is inadequately defended. Nc5 undermines Nf6 protector Nd7 while attacking Bb7 which is unprotected. Exchange of Nc5 with Nd7 provides no respite as Rd6 (another protector of Nf6) is attacked by a lowly pawn. Once Nd7 is undermined/exchanged, black's position collapses.

Harry

Yancey Ward said...

I have thought about this a bit more than I had done yesterday, and I think I have a slight improvement.

The critical line I found yesterday is...

1. Nc5 Bc8

And I proposed that 2.Nd7 is an error because the natural followup of capturing at f6 allows black a counterplay:

2. Nd7? Red7
3. Bf6?? Qe3!

And, as I outlined yesterday, white must block the check or get mated, or lose a piece if he defends more precisely after playing Kh1/h2. Now, I proposed the move of 2.Bf4, which wins an exchange. Though I had also consider 2.Bf5, I had not really gone beyond a couple of moves deep in it. This morning I took a second look for more detail:

1. Nc5 Bc8
2. Bf5 gf5 (alternatives below)
3. Nf5! Rde6 (or Ree6)
4. Ne6 Re6
5. Ng7 Kg7
6. Qh6 Kg8 (Kf7?? 7.Qh7+-)
7. Bf6 Nf6
8. Rf6 Rf6
9. Qf6 and white has won an exchange and a pawn, and has the black king completely exposed. This is surely won for white.

Now, black could refuse the offer of the bishop at f5:

1. Nc5 Bc8
2. Bf5 Nc5
3. bc5! Rd8
4. Bc8 Rc8
5. Bf6 Rf7!
6. Rfe1 and white has won a full piece. The real hole in this are the alternatives at move 3 in this variation. I looked at 3. ...Bxf5 can thought white wins, but it is complicated by the alternatives white has at move 4 in that line. If I have time later today, I will try to flesh them out.

ChittaB said...

I tried to play this for a while during weekend. Yes, Nc5 appears to be the best start for white but black can play on for quite sometime by sacrificing a rook.

This is how I went about it:

1. Nc5 Bc8
2. Qf4 Ree6
3. Nxe6 Rxe6
4. Bc2 Bf8
5. Qh4 Bg7
6. Bf4 Nb6
7. Qg5 Ne4
8. Nxe4 dxe4
9. Be3 Nd5

Still, objectively lost for black probably but will require accurate play from white for a long time.

It was very very tempting for me to use an engine - I will do that now.