Under promotion to a bishop.

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David Williams
Posts: 208
Joined: Sun Mar 29, 2009 8:37 pm

Re: Under promotion to a bishop.

Post by David Williams » Mon Dec 10, 2018 8:27 pm

Richard Bates wrote:
Mon Dec 10, 2018 3:52 pm
I’m struggling. Is the definitely the correct position?
Yes.

Richard Bates
Posts: 3009
Joined: Fri Nov 14, 2008 8:27 pm

Re: Under promotion to a bishop.

Post by Richard Bates » Mon Dec 10, 2018 8:32 pm

David Williams wrote:
Mon Dec 10, 2018 8:27 pm
Richard Bates wrote:
Mon Dec 10, 2018 3:52 pm
I’m struggling. Is the definitely the correct position?
Yes.
White to play and win?

EDIT: very nice.

Reg Clucas
Posts: 353
Joined: Mon May 16, 2011 3:45 pm

Re: Under promotion to a bishop.

Post by Reg Clucas » Tue Dec 11, 2018 1:56 pm

Richard Bates wrote:
Mon Dec 10, 2018 8:32 pm

EDIT: very nice.
Indeed. I got as far as the crucial promotion, at which point I thought that surely a Knight promotion is the only way to win, with a Bishop only drawing. But in fact the reverse is true.

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John Clarke
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Joined: Sat Apr 30, 2011 1:07 pm

Re: Under promotion to a bishop.

Post by John Clarke » Tue Dec 11, 2018 9:43 pm

Underpromotion to B where White has minimum K+P (study by Harold Lommer, date unknown).

White to win.

Lommer had a very amusing tale to tell about the difficulties he had composing this piece - see Assiac's The Delights Of Chess, where the study is reproduced on p22.

OK: if you had little or no trouble with that one, here's another that will really sort the men from the boys (and I'm definitely a boy when it comes to this sort of thing). Study by V A Korolkov, 1959.

White to win.

This is also in Assiac's book, where it's noted that Lommer had composed at least two other studies each featuring four separate underpromotions to Bishop. Maybe someone could track those down.
"The chess-board is the world ..... the player on the other side is hidden from us ..... he never overlooks a mistake, or makes the smallest allowance for ignorance."
(He doesn't let you resign and start again, either.)

David Williams
Posts: 208
Joined: Sun Mar 29, 2009 8:37 pm

Re: Under promotion to a bishop.

Post by David Williams » Thu Dec 13, 2018 8:40 am

Just to put this one to bed.



The stalemate position is easy enough for the composer to visualise, but to add just the two h pawns, to leave a position where two dark square bishops win, but one bishop, or bishop and knight don't? Brilliant. And note that after 7 Nb8=N+ Kb7, both 8 Na6, and 8 Nd7 Kc8 9 Nf8 both fail by a single move.

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