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1st January
2018

B P C F
2017





 
 
MatPlus.Net Forum Promenade A pawn remaining as a pawn upon promotion
 
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(1) Posted by Peter Wong [Sunday, Nov 12, 2017 00:35]

A pawn remaining as a pawn upon promotion


In a general chess forum, someone asked: what if it were legal for a P to "promote" to a P - are there situations where such a move would be the best? It turns out this was answered back in the 19th century when the rules were in dispute - see https://en.wikipedia.org/wiki/Promotion_(chess)#1862_British_Chess_Association_rule for a position where a P=P move is the only way to draw via stalemate.

Here's my attempt at the task. Can it be improved, e.g. done in miniature?

(= 2+6 )

1.e8(P)! and Black cannot stop the stalemate, while 1.e8(Q) would lose to 1...g3 2.Qg6 g2+ 3.Qxg2+ fxg2.

A P=P as the only move that WINS is much harder to set up, of course, but it turns out to be possible:

(= 9+10 )

Black threatens queen mates on a8 and f7. 1.exf8(Q/R)=. 1.exf8(B) Se7+ 2.S/Bxe7=. 1.exf8(S) Sxf6+ 2.gxf6=. 1.e8(Q) Qxf7+ 2.Qxf7 Se7+ 3.Q/Sxe7=. Engine analysis indicates that other white moves would actually lose. Therefore 1.exf8(P)!! avoids all stalemates and after 1...Sxf6+ 2.gxf6 Kh7, White is still a piece ahead and so wins the ending easily.

Does anyone know of precursors, or can anyone construct alternative positions?
 
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(2) Posted by Jan Hein Verduin [Sunday, Nov 12, 2017 12:18]

Of course there's this classic:

Sam Loyd
American Chess Magazine
dec. 1898

(= 9+3 )

±3

1.cxd8 pawn

and not:
1.cxd8Q/R? stalemate
1.cxd8B?,Bf5+!
1.cxd8S?,Bc6+!
 
 
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(3) Posted by Peter Wong [Sunday, Nov 12, 2017 14:31]

Thanks, Jan! I should've guessed that Sam Loyd had done something wacky like this. And I didn't even consider it could be done as a directmate!
 
   
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(4) Posted by Geir Sune Tallaksen Østmoe [Sunday, Nov 12, 2017 15:53]

I don't know about predecessors, but here is a miniature:

(= 2+5 )

Draw

1.f8Q? Sf4! wins as there are no checks, but 1.f8P! draws.

I also wondered if it is possible to make a study where both sides choose not to promote. That turned out to be easy by adding two pieces to your study:

(= 10+11 )

BTM, Win

1...gxh1Q 2.exf8Q wins easily since 2...Qxe4+ 3.dxe4 is not stalemate. But on 1...gxh1P!? White has to play 2.exf8P!
 
   
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(5) Posted by Peter Wong [Monday, Nov 13, 2017 06:27]

Both of your settings look good to me, Geir. In the second, it's remarkable that such a small adjustment results in two pairs of matched promotions. P=P moves by both sides is pretty funny!
 
   
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(6) Posted by Hauke Reddmann [Monday, Nov 13, 2017 09:46]

I really should not post after refereeing a chessmatch the day before;
I first overlooked Black is in check. :-)

But since with Geir it's personal (hey, the guy has a mere 200
ELOs more than me) I have to offer a setting with 6 pieces :-)

(= 2+4 )

1.c8Q? Qf3!

Hauke
 
   
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(7) Posted by Peter Wong [Monday, Nov 13, 2017 11:12]

Nice one, Hauke. I like how 1...Qh8 mate is stopped by the key.
 
   
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(8) Posted by ichai [Monday, Nov 13, 2017 12:04]; edited by ichai [17-11-13]

(= 2+4 )

a) diagram
b) c3->c4

a) c8=P=
(1.c8=Q? Bc4! wins)

b) c8=Q=
(1.c8=P? R2c3!)
1.c8=Q! Rb4 2.Qb8! R2c4 3.Qe8! Re4 4.Qc6+! Kd1 5.Kxa2!=

a step to auw?
 
   
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(9) Posted by Hauke Reddmann [Monday, Nov 13, 2017 22:12]

Nice find! When I searched the matrix I didn't have the guts
to place another rook inmid the botanics :-)
 
 
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(10) Posted by seetharaman kalyan [Tuesday, Nov 14, 2017 04:12]

This is just brilliant!
 
   
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(11) Posted by Hauke Reddmann [Tuesday, Nov 14, 2017 11:59]

Since we are screwing with the rules anyway...
(= 3+3 )

#1, a) Dia: 1.gxh8=bR b) -Sg8, 1.g8=bS
...this joke is way old. Can you motivate a promotion to
black bishop (yes, but I didn't flesh out the details)
or even queen? In a study? (Note in a) we
can promote to bP too, but we break one rule at a time :-)

Hauke
 
   
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(12) Posted by Hauke Reddmann [Sunday, Nov 19, 2017 13:48]

(= 4+4 )

And a last one. This is an old study of mine from our club zine
INSELSCHACH, which just extends a well-known trick.
1.Ke6! h5 2.gxh5 g4 3.Kf5 g3 4.Kg6 g2 5.Kh6 =
Clearly 5...g1Q,R stalemates, g1B is a well known fortress
and even the most dangerous g1S is drawn after 8...Sxa2 9.Kd4
since a2 soon will be forced with another fortress.
The winning move, clearly and obviously, is g1K,
feel free to find a more economic setting :-)
 
 
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MatPlus.Net Forum Promenade A pawn remaining as a pawn upon promotion