Monday, May 05, 2014

BORP? XXX

White to play

I don’t know about your first impressions of this position, but mine were,"Well I don’t see a mate yet, but surely Black must be in trouble here." White is down an exchange, but Black’s pieces are sleeping in their beds. Black has a mate in one on, but White has the move. Black’s king is trapped against the ropes, but … but nothing.

Surely this must be good enough for White?

If you check this with your engine, or your own brain if you’re so inclined, you’ll see that 1. Qxh7+ and 1 h4+ both lead to mate. In 11 and 8 moves respectively according to HIARCS. In a game you wouldn’t know that, though, would you?

Is 'surely this must be good enough' good enough?

White to play

Geoff Chandler gives this position in his chapter on tactics in MASTER CHESS: A Course in 21 Lessons (Pergammon Press, 1985). White had calculated a three-move variation that involved sacrificing a piece to get here. Apparently it was only when the game actually arrived at this point that he worked out what he was going to do next.

Chandler writes, that weaker players often miss the chances for play this kind of attack precisely because they can’t work everything out in advance. Stronger players, he says,

" … will sometimes not bother to try to analyse all the possible variations, he will simply know that a king out in the open, at the mercy of an attacker’s army, rarely survives."

Let’s go back to our original position. Don’t worry where it comes from. We’ll get to that in a couple of weeks.

All you need to know is that to get here you’ll have to sacrifice an exchange and calculate a fairly long variation. It’s pretty forcing so even no-mark bloggers can do it. Now things get more difficult because you have to start making choices (h4?; Qxh7?) and because that chessboard in your mind’s eye is getting a little hazy.

In fact, let’s say you can’t reliably calculate any further so you’re going to have to make your choice based on what you see here. Without knowing for sure.

I’d go for it. I might not have found the mate, but you don’t need to see the future if you know it’s there.

No exchange sacrifice for me. I’d have to be 100% certain.

2014 ISE COUNT: 39
TISE INDEX
BORP? INDEX

Anonymous said...

It might depend on how badly you wanted to win, but it's clear enough that even if there isn't a forced mate, White will have a draw at least.

Almost every game, you get a decision point where you don't know if your continuation will win, but you are moderately certain it keeps a draw in hand.

RdC

John Cox said...

If you really can’t calculate any further than this then it’s hard to go for this position, since it isn’t stable – Black is threatening mate and the knight, so if White isn’t winning probably he’s losing.

I’d say you have to see at least 1 Qxh7+ Kxg5 2 Bc1+. After that it’s really not hard to see that White can at least drive the king to the d-file and skewer the black queen. Mate’s harder – in fact I don’t see it myself, though that’s probably because you wouldn’t really look.

You could try it on the basis something must turn up, I suppose. It does strike me as a bit random on this particular occasion.

Anonymous said...

I found this BORP thought provoking, but I did not agree the comparison between the two positions is correct. So I agree with John Cox. I think his comment about stability is well made. Really in the first type of position you just have to keep calculating, and accept if your calculating ability is limited it will cost games.

I was not sure if Jonathan was asking for advice in a couple of the other ISE posts, where he expressed frustration, and wondered if the subject was suitable for a player of his strength. For what it is worth, I think it is worth persevering. But in my opinion the amount of material sacrificed is less important than the reason it is sacrificed, and so far there has been a very mixed bag of sacrifices.

The first type here, requiring concrete calculation can occur from any type of sacrifice. I do not think these positions are relevant to only those who want to attack; it is possible to win games by allowing incorrect sacrifices. But they are likely to be decided by the player who can calculate better.

The second type here, where the sacrifice is for an attack but position is unclear and needs assessment does not always favour the person with greater calculating ability, Botvinnik is very instructive for the positional player, the famous Tal knight sacrifice comes to mind. But again I think calculation counts for a lot. The GMs don’t show you the games where they had the draw in hand, and took it because they could not find a line to back up their intuition.

The third type, for positional compensation, are the ones which I think players like me and Jonathan need to try to master. Knowing how much weight to give to a shattered pawn formation and how to exploit it, and how to exploit domination of a colour complex, are ways to win games. Again I think the material less important than the type of compensation. For example, giving up a rook for a bishop to dominate dark squares probably has more in common with Ulf playing Bg5xNf6 and winning on the light squares, than it does with sacing a rook for a knight on kings bishop three.

Possibly the Petrosian sacrifice is just an example of the third type. But his sacrifices that change what the game is about – that it was about a white kingside attack but changed to be about blacks centre - are on a higher level. The classic 1953 Reshevsky-Petrosian game is stunning in that respect. I’ve no advice to offer on how to play these, and I hope Jonathan can enlighten me! :-)

Paul C

ejh said...
Jonathan B said...

@Roger: Yes, in reality it all depends, of course. On the match situation, on the tournament situation, on how much you’re in the mood etc etc.

What I was trying to get at was the general point of using judgement against concrete analysis at some point as much as this specific situation.

@John: The skewer idea hadn’t occurred to me. Funny you should mention it, though, as next week’s post (I think, but it might be the week after) is how I fail to notice that I can switch targets like that.

@Paul: That’s an interesting comment. I do wonder if I have ideas above my station in this area, but then again it always will be beyond me unless I trying to get some kind of grasp of it.

That last type of comment is the kind of problem I see creating for myself, though. E.g. I can envisage a scenario where I’d sacrifice an exchange in order to, say, give my opponent broken pawns. This could well be 'correct', but then I go on and lose anyway because I simply lacked the ability to exploit the advantage that I’d created for myself.

I had thought that I should move on to this kind of ISE, though. I’ve got a couple more planned on the current theme and then let’s see what’s what.

Matt Fletcher said...

I think I'd play it after a long think, although I'd try to get a little bit further than the position shown.

My latest blog post (from about 6 weeks ago, must get round to doing another one) covers reasonably similar ground with a piece sacrifice at move 16:

http://learnfromtheamateurs.blogspot.co.uk/2014/03/calculations-what-you-need.html