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Underpromotion



 
 
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  #1  
Old July 10th 03, 10:20 AM
Dougy
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Default Underpromotion

Question: Is there any proper reason, ever, to underpromote to a R or
a B? (ie. excluding just for wit, assuming proper play)

I've seen plenty of reasons for promoting to a N or a Q but never a R
or a B. Obviously the check or forking advantage of a knight doesn't
work in the case of a rook or a bishop because a queen can do that
also.

However I can picture (fuzzily) something along the lines of piece
placement, and by underpromoting to a R or a B it may make the
opponent attack another piece other than the promoted one, (eg. a
knight capturing a rook in the corner insead of a bishop) A weird
kind of sacrifice. Or where it is desperately needed to control a
square where a bishop is stronger than a queen.

What i'm after is a setup where it would be conceivably beneficial to
underpromote to R or B.

Thanks in advance

Dougy
  #2  
Old July 10th 03, 10:36 AM
Aldert-Jan Keessen
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Default Underpromotion

The main reason for an underpromotion is to prevent stalemate. For example:
wK: f6, wp:f7
bK: h7

If white were to play f7-f8Q it would be stalemate, f7-f8R would be mate on
the next move.

See for more examples:
http://www.xs4all.nl/~timkr/chess2/minor.htm

Dougy wrote:

Question: Is there any proper reason, ever, to underpromote to a R or
a B? (ie. excluding just for wit, assuming proper play)

I've seen plenty of reasons for promoting to a N or a Q but never a R
or a B. Obviously the check or forking advantage of a knight doesn't
work in the case of a rook or a bishop because a queen can do that
also.

However I can picture (fuzzily) something along the lines of piece
placement, and by underpromoting to a R or a B it may make the
opponent attack another piece other than the promoted one, (eg. a
knight capturing a rook in the corner insead of a bishop) A weird
kind of sacrifice. Or where it is desperately needed to control a
square where a bishop is stronger than a queen.

What i'm after is a setup where it would be conceivably beneficial to
underpromote to R or B.

Thanks in advance

Dougy

  #3  
Old July 10th 03, 11:51 AM
John Fernandez
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Default Underpromotion

Question: Is there any proper reason, ever, to underpromote to a R or
a B? (ie. excluding just for wit, assuming proper play)


Yes, stalemate avoidance.

John Fernandez
  #4  
Old July 11th 03, 05:36 AM
Dougy
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Default Underpromotion

Ahh okay, thanks! (:

Aldert-Jan Keessen wrote in message ...
The main reason for an underpromotion is to prevent stalemate. For example:
wK: f6, wp:f7
bK: h7

If white were to play f7-f8Q it would be stalemate, f7-f8R would be mate on
the next move.

See for more examples:
http://www.xs4all.nl/~timkr/chess2/minor.htm

Dougy wrote:

Question: Is there any proper reason, ever, to underpromote to a R or
a B? (ie. excluding just for wit, assuming proper play)

I've seen plenty of reasons for promoting to a N or a Q but never a R
or a B. Obviously the check or forking advantage of a knight doesn't
work in the case of a rook or a bishop because a queen can do that
also.

However I can picture (fuzzily) something along the lines of piece
placement, and by underpromoting to a R or a B it may make the
opponent attack another piece other than the promoted one, (eg. a
knight capturing a rook in the corner insead of a bishop) A weird
kind of sacrifice. Or where it is desperately needed to control a
square where a bishop is stronger than a queen.

What i'm after is a setup where it would be conceivably beneficial to
underpromote to R or B.

Thanks in advance

Dougy

  #5  
Old July 11th 03, 12:54 PM
santa
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Default Underpromotion

your post comes here
7k/5P2/8/5K2/8/8/8/8 w - - 0 1

in this position the quickest victory comes with

1. Kf6 Kh7
2. f8=R Kh6
3.Rf8#

so people underpromote in situations when they find it more benefecial than
promotion to a queen as well.



  #7  
Old July 21st 03, 10:36 PM
dan foley
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Default Underpromotion

(Dougy) wrote in message . com...
Question: Is there any proper reason, ever, to underpromote to a R or
a B? (ie. excluding just for wit, assuming proper play)

I've seen plenty of reasons for promoting to a N or a Q but never a R
or a B. Obviously the check or forking advantage of a knight doesn't
work in the case of a rook or a bishop because a queen can do that
also.

I recall a study by Rusinek in which white had to underpromote to a
knight, a bishop, and then a rook in order to DRAW. The point was
that in the case of the knight, promotion with check was necessary to
avoid mate, and with the bishop and rook underpromotions, a queen
would have proven TOO STRONG and would have had too many legal moves,
again allowing checkmate ... whereas stalemate resulted with the
underpromotions. I will look up this study and send it to you (am in
the process of unpacking boxes, once I find it will give it to you)

Now on a lighter note, I remember an incident from when I was a
teenager involving bishop underpromotion. An expert and an "A" player
were paired in a local tournament. In this particular game the expert
was frustrated as he had an extra Bishop and his opponent was still
playing on. Expert simplified down to a position where he had a king,
bishop, and pawn versus a lone king...and STILL the A player wouldn't
resign! Expert nursed the pawn to the 7th rank, and in a gesture of
contempt...underpromoted to a bishop. Only AFTER slamming the newly
born bishop down on the last rank and hitting his clock did he
realize...IT WAS ON THE SAME COLOR AS THE OTHER ONE.
  #8  
Old July 22nd 03, 12:44 AM
Louis Blair
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Default Underpromotion

I am surprised that I have not seen anyone mention perhaps
the most famous example of this sort of thing:

- - - - - - - -
- - - - - - - -
- K P - - - - -
- - - r - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
k - - - - - - -

1 c7 Rd6+ 2 Kb5 Rd5+ 3 Kb4 Rd4+ 4 Kb3 Rd3+ 5 Kc2 Rd4
6 c8

and now, white can not take a queen because of the possibility
of 6 ... Re4+. The only way to win is for white to take a rook
and then comes 6 ... Ra4 7 Kb3 and it is all over.

See

http://www.xs4all.nl/~timkr/chess2/rynd.htm

for more about this position.



  #9  
Old July 22nd 03, 12:47 AM
Louis Blair
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Default Underpromotion

I wrote:

I am surprised that I have not seen anyone mention perhaps
the most famous example of this sort of thing:

- - - - - - - -
- - - - - - - -
- K P - - - - -
- - - r - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
k - - - - - - -

1 c7 Rd6+ 2 Kb5 Rd5+ 3 Kb4 Rd4+ 4 Kb3 Rd3+ 5 Kc2 Rd4
6 c8

and now, white can not take a queen because of the possibility
of 6 ... Re4+. The only way to win is for white to take a rook
and then comes 6 ... Ra4 7 Kb3 and it is all over.

See

http://www.xs4all.nl/~timkr/chess2/rynd.htm

for more about this position.


_
Of course, I should have written, "and now, white can not take
a queen because of the possibility of 6 ... Rc4+."


  #10  
Old August 1st 03, 05:50 PM
dan foley
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Default Underpromotion

I've seen plenty of reasons for promoting to a N or a Q but never a R
or a B. Obviously the check or forking advantage of a knight doesn't
work in the case of a rook or a bishop because a queen can do that
also.

Here is the Rusinek study I referred to. Enjoy.

Study by Rusinek, 1971
White to Play and Draw
Black: Nc3, Nd7, Ke7, Bc4
White: Kc8, Pb6, Pa6, Pc7, Pg7

White has 4 pawns poised to promote, but Black has mate threats.

1. a7! Ba6+

(1. Bd5; 2. g8N+! Ke8; 3. Nf6+! Nf6: ; 4. a8Q Ba8: 5. b7 =)

2. b7 Ne4!

(2. Nb5 3. g8N+! Ke8; 3. Nf6+! Nf6: ; 4. a8Q )

3. g8N+! Ke8
4. Nf6+! Nef6:

Now, if 5. a8Q Nd5!! 6. any Ne7#

5. a8B!! .

Creating a stalemate.

5. Ne5!
6. Kb8 Nc6+
7. Kc8 Bf1!

Now if 8. b8Q (or b8B) Ba6+ 9. Qb7 Ne4! 10. any Nd6#. 8. b8N Ne7 9.
Kb7 Bg2+ 10. Ka7 Nc8+ 10. Ka6 Ba8: winning for black.

8. b8R!! Ba6+
9. Rb7!

With a draw, as black must either stalemate white or allow the
material balance to be equal.

Brilliant it's next to impossible to create underpromotions
necessary to DRAW, and to have three different such underpromotions in
a gamelike position is just marvelous. This is my favorite study.
 




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