Under promotion to a bishop.

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Robert Stokes
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Under promotion to a bishop.

Post by Robert Stokes » Sun Dec 09, 2018 6:09 pm

We all know that when a pawn reaches the eighth rank it is normally promoted to a queen. There are rare cases where this would produce stalemate so a rook is preferred. There are even rare cases where promotion to a knight is preferred if it can produce an immediate mate in a situation where no other piece can do this. However, I have never read about a pawn being promoted to a bishop so I set myself a problem. Could I devise a position where promoting a pawn to a bishop is the most sensible move. I think I have done this. Consider the following position.

FEN 5bkr/4p2p/1P2P2P/8/2p5/8/8/R1K5

(I hope that I have got the FEN notation correct - if not white, to play has Ra1, Kc1, and pawns b6, e6, h6 and black has Rh8, Kg8, Bf8, and pawns c4, e7, h7.)

White can see that, unless he prevents it, black's next move will be Bxh6+, followed by Kg7, thus freeing his rook. To prevent this he plays Ra8 and black now plays his only legal move c3. White now plays b7 and black must play c2. We now have this position. (This was the one I originally devised, but I wanted to show how it could have occurred.)

FEN R4bkr/1P2p2p/4P2P/8/8/8/2p5/2K5

Black now has no legal move so if white wants to play for a win, his next move must give black a legal move. There are two ways to do this - move the rook off the eighth rank or promote the b pawn to a minor piece. If he chooses the former, then black will play Bxh6+ followed by Kg7 freeing his rook as mentioned above. I suggest that from this position the result of the game is not clear.

Now consider white playing b8=B. Black can only move his bishop and will play Bxh6+ but after Kxc2 if he plays Kg7 it is met by Be5+ and black goes a rook down. His only alternative is to move the bishop again and I think that wherever it goes white has a winning reply.

Do you agree with this analysis? Have I found a position where promoting a pawn to a bishop is the best possible move?

Mick Norris
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Re: Under promotion to a bishop.

Post by Mick Norris » Sun Dec 09, 2018 6:10 pm

Any postings on here represent my personal views and should not be taken as representative of the Manchester Chess Federation www.manchesterchess.co.uk

Mick Norris
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Re: Under promotion to a bishop.

Post by Mick Norris » Sun Dec 09, 2018 6:11 pm

Any postings on here represent my personal views and should not be taken as representative of the Manchester Chess Federation www.manchesterchess.co.uk

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IM Jack Rudd
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Re: Under promotion to a bishop.

Post by IM Jack Rudd » Sun Dec 09, 2018 6:12 pm

3.b8B is winning, but 3.Rxf8+ is rather better.

Robert Stokes
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Re: Under promotion to a bishop.

Post by Robert Stokes » Sun Dec 09, 2018 6:16 pm

Yes, I missed that.

Can anyone adapt my position or devise their own where there is no better move than promotion to a bishop?

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Matt Mackenzie
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Re: Under promotion to a bishop.

Post by Matt Mackenzie » Sun Dec 09, 2018 6:22 pm

Tim Krabbe's site gives examples of "genuine" R and B underpromotions.

The latter in particular is indeed extremely rare, but as he shows not totally unknown.
"Set up your attacks so that when the fire is out, it isn't out!" (H N Pillsbury)

NickFaulks
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Re: Under promotion to a bishop.

Post by NickFaulks » Sun Dec 09, 2018 6:29 pm

Is this any good?


bishop promotion.PNG
bishop promotion.PNG (18.26 KiB) Viewed 1056 times

Richard James
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Re: Under promotion to a bishop.

Post by Richard James » Sun Dec 09, 2018 8:10 pm



This is Harry Bogdanor - Bertram Goulding Brown BCF Major Open Chester 1914.

The loser of this game features here.



This position has happened quite often. One example with an English connection is Alfred Beni - John Littlewood Clare Benedict Cup 1963.

On a more frivolous note, the other day I reached a position like this (there were a few blocked pawns as well) in a training game against two pupils. It wasn't the quickest win, but I chose to promote to a bishop so that I could teach them the two bishops mate.


David Williams
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Re: Under promotion to a bishop.

Post by David Williams » Sun Dec 09, 2018 11:56 pm


If you want to see a very special under-promotion to a bishop, try solving this study by Troitsky.

Geoff Chandler
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Re: Under promotion to a bishop.

Post by Geoff Chandler » Mon Dec 10, 2018 10:56 am

Recall Ray Keene under promoting to a Bishop to see if what publication
actually got it right. I think he was writing in CHESS at the time.

Later at chessgames Ray said it appealed to his sense of humour

D. Yanofsky - R. Keene, Olympiad 1974.



Ray played 49...a1=B, Yanofsky took it Ray then checked on d2
and e3 taking on f4 winning the pinned Knight.

http://www.chessgames.com/perl/chessgame?gid=1071383

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JustinHorton
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Re: Under promotion to a bishop.

Post by JustinHorton » Mon Dec 10, 2018 11:16 am

Sense of irony more like
"Do you play chess?"
"Yes, but I prefer a game with a better chance of cheating."

lostontime.blogspot.com

Geoff Chandler
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Re: Under promotion to a bishop.

Post by Geoff Chandler » Mon Dec 10, 2018 11:34 am

Thanks Justin,

It was CHESS that got it wrong. I knew it figured.

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Matt Mackenzie
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Re: Under promotion to a bishop.

Post by Matt Mackenzie » Mon Dec 10, 2018 2:45 pm

Richard James wrote:
Sun Dec 09, 2018 8:10 pm


This position has happened quite often. One example with an English connection is Alfred Beni - John Littlewood Clare Benedict Cup 1963.
Of course the more common Knight underpromotion would win here as well as the Bishop.
"Set up your attacks so that when the fire is out, it isn't out!" (H N Pillsbury)

Reg Clucas
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Re: Under promotion to a bishop.

Post by Reg Clucas » Mon Dec 10, 2018 3:46 pm

There was a study in CHESS magazine some time ago which featured 3 or 4 promotions to a bishop. But don't ask me which issue!

Richard Bates
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Re: Under promotion to a bishop.

Post by Richard Bates » Mon Dec 10, 2018 3:52 pm

David Williams wrote:
Sun Dec 09, 2018 11:56 pm

If you want to see a very special under-promotion to a bishop, try solving this study by Troitsky.
I’m struggling. Is the definitely the correct position?

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