Tuesday, January 20, 2009

Nuance


Güetas-Horton, SMA Barbastro v Casino Jaque, Copa Delegación semi-final 2009, board one: position after 20.dxc5?!.

Black can recapture with the bishop or the knight. Which do you prefer - and why?

22 comments:

Tom Chivers said...

I prefer the knight, but don't know why.

Anonymous said...

I prefer the bishop, but dont
know why.

George

Anonymous said...

Is George taking the piss?

ejh said...

The "why" is the whole point when you're sitting at the board, as I was.

Will said...

I prefer the knight since it opens up the file for the rook behind creating a fresh double attack on the light bishop. I guess all of blacks pawns are on light squares so keeping the dark bishop is better?

1 Nxc5 Rd1 (1 ... Bxc5 2 Bxc5 -/+) 2 Nxd3 Rxd3 3 Bxc3 bxc3 4 Nxe4

Close?

Tom Chivers said...

The "why" is the whole point when you're sitting at the board, as I was.

Interesting comment! Is it?

ejh said...

Is it?

Yes, I think so: you have to choose between the two, and it's possible it's a tactical choice, not merely one of stylistic preference.

I'm not sure I follow Will's moves, but if he's saying that 1....Bxc5 is met by 2.Bxc5 with a large White advantage, I'm not entirely sure he's right.

Tom Chivers said...

Ah ok. I thought you meant more broadly, i.e., that whenever you make a move the main thing is knowing why you make it. I'm not sure that can quite be the case.

Anonymous said...

Without giving it too much thought, I would take with the Knight. My reasoning would be that it retains some measure of initiative in that White has to respond -whereas taking with the Bishop can be ignored if White has a good move somewhere else. Other factors would be that White giving up the Bishop for the Knight with Bxc5 could favour Black because of the resulting control of the dar squares. Also the squares round Black's king feel a little sensitive with the Black bishop miles away on b4.

RdC

ejh said...

And does White have a good move somewhere else?

Anonymous said...

Actually there had to be a point to Ra2 and I imagine that it's to double on the a-file with Rg1-a1 with threats to win the a pawn directly and the b pawn indirectly whether Black takes on c5 with the B or the N or doesn't recapture. So it looks as if White does have an initiative move of his own so 1.. Nxc5 2 Bxc5 Bxc5 3 Rg1a1 or 1 .. Bxc5 2 Rg1a1

A long think looks to be in order trying to calculate or uncover defences or compensation to the threat of winning the pawn. If short of time or lazy, taking with the Knight might still be best on the grounds that it's better to be a pawn down with a bishop pair than without.

RdC

Jack Rudd said...

The difference is that after 1...Nxc5 2.Bxc5 Bxc5 3.Rga1, black can respond with 3...Bxf2!, so he doesn't lose a pawn.

Anonymous said...

I think white's light-squared bishop looks like quite a defensive piece so the Knight on c5could be a "good knight versus bad bishop" (especially with a dodgy b3pawn). However white's dark-squared bishop can take the knight if it goes first, so take with the bishop...

GM (not a real one)

Anonymous said...

I'd take with the Knight as instinctively feels like it would be nice to have the d7 square for the other knight in case of an e4-e5 push but I can't give any concrete variations

Phil McCracken

Will said...

"I'm not sure I follow Will's moves"

In mst of my games neither do I, which explains why my grade is closer to 100 than 150

Anonymous said...

The d7 knight looks very strong on c5 if white can't exchange his bishop for it.

How about 1 ..BxP.

Some lines might be.

2.BxB NxB; Bc2 and black can try b4 to win the e4 pawn.
2.Rga1 BxB; 3.PxB Nc5
2.e5 BxB; 3.PxB Nc5 etc
2.Bd2 Bd4; 3.Rga1 Nc5; 4.Nxb5 Bxb2

-Richard

ejh said...

OK. I reckon Phil's the closest, in fact.

The basic idea is that 20...Nxc5 (my original intention) is good and 20...Bxc5 (the move I played) is bad. I switched because I wanted to menace the bishop on d3 and wasn't clear what would happen if White took on c5: so I took with the bishop, enabling me to capture on e3 and then play ...Nc5. However, as RdC suggests, there's an initiative move for White in the interim, which is (as Phil surmised) e5, which I saw only after playing 20....Bxc5 and which:

(a) forces my f6 knight to a poor square before I can do anything significant with the d7 knight (22...Nc5 23.Bc2 doesn't change anything) ;

(b) opens up the e4 square for the bishop.

(This is also, unfortunately, why Jack's capture on f2 - not that I saw it, mind - doesn't work, since White plays e5 and after the d3 bishop can move to e4, it's no longer attacked, but both the rook and the f2-bishop are.)

The actual continuation was 20...Bxc5 21.e5! Bxe3 22.fxe3 Nd5?! (I think Black must lose a pawn, but this may not be the best way) 23.Nxd5 exd5 24.Rdc1 and despite some ingenuity Black lost the ending (crucially, since we lost a drawn match on tiebreak).

Stronger was 20...Nxc5! after which 21.Bxc5 Bxc5 22.Rga1 fails to 22...b4! and Black wins by doubling rooks on the d-file. (22.e5 is no longer effective because after 22...Nh5 the f4 pawn is menaced.) The Bc2 idea fails to 21...Bxc3 because e4 is threatened, as the f6 knight has not been driven off. And 21.e5 is weaker than it is after the bishop capture, although it may be White's best drawing chance. 21...Nxd3 22.exf6 Nc5 23.Bxc5 Bxc5 24.Rga1 (or 24.Ne4 Bb4) Rd4 and the pawn on f6 is not as frightening as it looks.

I'm vaguely reminded of this debacle in which I similarly chose the move than lost, rather than the more obvious one that probably won, though trying to be too clever. We never learn, do we?

ejh said...

(Note: I was going to do this one for the Miss Easy Tactics! series, but given that the outcome isn't absolutely clear I eventually decided against.)

ejh said...

(Also apologies to Richard, who must have posted while I was writing my comments. I think his line

2.e5 BxB; 3.PxB Nc5 etc

fails to 4.Bc2 after which the f6 knight doesn't really have a good square.)

Anonymous said...

In the variation Nxc5 i think Bb1 gets d column safe , if Bxc3. Bxc5.
Ithink black have to avoid e5 trying at first e5.Then if c6.exf4,Bxf4.Nc5,Bb1.Bxc3,bxc3.Nfxe4
If fxe5 then Nxe5,Bb1.Nfg4(Neg4,e5!),Nd5.Nxe3,Nxb4.a5,f4.Neg4

ejh said...

If Bb1 Nxb3.

Anonymous said...

It wasn't me, just for the avoidance of doubt.

Richard