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kamus - Basic ending:RvsB [13:15] 
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Post kamus - Basic ending:RvsB [13:15]
Poster: kamus
Rating Class: Class B (1600-1800) | Videos Made: 241
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Video Tags: basic endgame technique right corner rook vs bishop wrong corner

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Sat Apr 17, 2010 11:55 am
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Post Re: kamus - Basic ending:RvsB [13:15]
These are very basic endgames that you can skip if you're intermediate/advanced and you already know the basic ideas. This is a public service to those players who are just learning the basics of endgame play.

I added these positions to the endgame simulator:

Draw with white: White king in the right corner

Win with white:Black king in the wrong corner

BTW why are all my videos coming out squished- this didn't happen before but lately it's been messed up.

edit: xitvono pointed out at least one error in my analysis- see our posts below. Fortunately it is in a sideline and (I hope) doesn't mess up the main thesis of the video.

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Sat Apr 17, 2010 12:03 pm
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Knight

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Post Re: kamus - Basic ending:RvsB [13:15]
Excellent video. I imagine there would be many an intermediate player that doesn't know "the wrong corner".


Sat Apr 17, 2010 2:33 pm
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Knight

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Post Re: kamus - Basic ending:RvsB [13:15]
Nice overview of the rook vs bishop ending. There's actually a couple of mistakes in the analysis. First, where you say that white shouldn't play kf5 with the double attack, white can still win even after black plays bg7 as the king is still in the danger zone. Also, later on you mention re2 wins too (with Be7 and kings on g6,g8) but black draws with kf8. I think that there's certainly more subtlety than simply good corner draws and bad corner loses, as often if black has his bishop on the long diagonal that can save him when his king is in the bad corner since it controls the key square f6. I like where you point out that be6 in the good corner position is bad because of the need to give a check. That's a good example of subtlety in this ending. Good luck with the rook vs knight ending.


Sat Apr 17, 2010 6:10 pm
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Post Re: kamus - Basic ending:RvsB [13:15]
xitvono wrote:
... where you say that white shouldn't play kf5 with the double attack, white can still win even after black plays bg7 as the king is still in the danger zone. Also, later on you mention re2 wins too (with Be7 and kings on g6,g8) but black draws with kf8.


Thanks for the comments xitvono- I'll have to disagree about your first point though. Apparently, Black can eventually escape to the good corner with best play from white. I checked it with Rybka 3 and it seems to agree- (though neither I nor Rybka are the last word in endgame analysis :) ). If you can post some supporting analysis that proves your contention, I would be very interested in that and would be happy to concede the point.

On your second point, you are 100% correct and I was guilty of superficial analysis there. I don't want to redo the video for the sake of the error(s) but I will amend my opening post to reflect your observation.

Also, you are correct about there being more subtlety than just "bad corner loses". The example I gave was one of the positions that does lose in the bad corner. As Jesus DeVilla points out in his excellent endgame book, nearly all R v B endings are drawn but the defending side introduces losing chances by being in the "wrong corner" whereas in the "right corner" there are zero chances to lose as long as the defender plays reasonably accurately.

Thanks again for watching and commenting.

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Sat Apr 17, 2010 7:38 pm
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Knight

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Post Re: kamus - Basic ending:RvsB [13:15]
I think the position I am thinking of is when white attacks the bishop with kf5, the bishop is on e5, the black king is on g8 and the rook is on g1. While kf5 is not the quickest or most logical move, after bg7 white can play kg6 and black can't get out of the bad corner as kf8 drops the bishop.


Sun Apr 18, 2010 1:12 am
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Post Re: kamus - Basic ending:RvsB [13:15]
xitvono wrote:
I think the position I am thinking of is when white attacks the bishop with kf5, the bishop is on e5, the black king is on g8 and the rook is on g1. While kf5 is not the quickest or most logical move, after Bg7 white can play kg6 and black can't get out of the bad corner as kf8 drops the bishop.


Well OK it turns out that you are correct on that point too! The really odd thing is when I did the video, I checked this analysis with two engines: Rybka 3 and Hiarcs 12. After Kf5 Bg7 in the position you describe (which incidentally has the rook on g2 , not g1), both engines give the draw to black. Both engines suggest Ke6(??) for white which draws, but if you manually put in Kg6 instead then all of a sudden, it's a win for white!? That's a very weird case of chess blindness from two strong programs. Even weirder is that if you change the position so the rook is on g1, then both programs have no trouble spotting the win.

When I did the video, I briefly looked at the move Kf5+ and simply trusted the analysis of the two engines- if I had gone one move further I would have spotted the win. Thanks for bringing this to my attention. I may redo the video to fix these blemishes.

I can tell you that I'm going to be a lot more wary of engine analysis from now on. If you can't trust Rybka, who can you trust? Perhaps there is an engine somewhere that specializes in endgame analysis.

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Sun Apr 18, 2010 8:13 am
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Knight

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Post Re: kamus - Basic ending:RvsB [13:15]
If you're going to do analysis on this ending, you should probably use an endgame tablebase. You can use it online at a place like the shredder website.


Sun Apr 18, 2010 9:35 am
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Rook

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Post Re: kamus - Basic ending:RvsB [13:15]
I have personal experience in this endgame from a tournament game last year. I had the rook versus the bishop against a 2200 and he got to right corner and I still managed to get him to blunder in extreme time pressure. So, these are very good things to know and practice certainly makes, at least close to, perfect.


Sun Apr 18, 2010 10:23 pm
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