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MatPlus.Net Forum Retro/Math Promotions in the proof-game of an orthodox direct-mate
 
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(1) Posted by Ian Shanahan [Wednesday, Jan 2, 2013 03:14]; edited by Ian Shanahan [13-01-02]

Promotions in the proof-game of an orthodox direct-mate


In this thread - http://matplus.net/pub/start.php?px=1357090541&app=forum&act=posts&fid=gen&tid=1130 - a discussion ensued concerning whether or not promoted force appearing in the proof-game of an orthodox directmate (all such promotees having been captured before the diagram position was reached) is regarded as a flaw. I have nowhere seen absent promotees adversely criticized, and it has never been an issue for me before - until now. Over Christmas, I composed a "mammoth" #2 {13+13} with the following Pawn-configuration (note that all of the Black and White PIECES - except for the bQ - are present elsewhere):

(= 5+6 )


(Remember that all 8 White pieces and 7 Black pieces apart from the Q are on the board.) Now the Pawn configuration accounts for all 6 missing units - 3 for each side. White has captured either on the ccd- or the cde-files: [Qd8]; [Pa7] or [Pg7]; and [Ph7] - so [Ph7] and one of the other bPs ([Pa7] or [Pg7]) must have promoted without making any captures before themselves being captured somewhere on the c-, d- or e-files. Black has captured either on the bcd- or the def-files: [Pa2]; [Pb2], [Pd2] or [Pf2]; and [Ph2] - so at least [Pa2] and [Ph2] must have promoted without making any captures before themselves being captured somewhere on the b- to f-files. Therefore, in every conceivable proof-game scenario, [Ph2] and [Ph7] must have promoted without making any captures. But this is impossible, because they could never have moved past each other to reach their respective promotion-squares h8 and h1. So the position is ILLEGAL.

I discovered that I could legalize the position without loss of content by eliminating the bPc5 and deploying the bQ:

(= 5+6 )


Here, bPd4 captured [Pd2], wPc4 is [Pb2], wPd7 is [Pf2], and wPg4 is [Pg2] - leaving [Pa2] and [Ph2], which were captured; White has captured [Pa7], [Pg7] and [Ph7] - all of which must have promoted before themselves being captured somewhere on the c-, d- and e-files. [Pa7] promoted on a1 without making any captures after [Pa2] was captured on the a-file by some other man; [Pg7] captured [Ph2] (only) on the h-file, promoting on h1, after which [Ph7] promoted on h1 without making any captures. So the position is legal - albeit with THREE obtrusive Black pieces that promoted on a1 and h1 but have since disappeared! Most amusing!

For anybody who is interested, the problem (a #2, dedicated to Eugene Rosner) will be published in "The Problemist" later this year.
 
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(2) Posted by Hauke Reddmann [Wednesday, Jan 2, 2013 12:44]

Well, using an officer instead of a pawn to legalize a cramped pawn structure
is not exactly the 12 o'clock news (I speak from personal experience)
but this is a rather extreme case, I admit :-)

Hauke

P.S. So, what do you pay to me that I don't retroengineer you 2#
just from the pawn structure and snitch it? :-))
 
 
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(3) Posted by Eugene Rosner [Thursday, Jan 3, 2013 00:08]; edited by Eugene Rosner [13-01-03]

see below!
 
 
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(4) Posted by Eugene Rosner [Thursday, Jan 3, 2013 00:09]

that would be akin to what Woody Allen tried to do in the movie "Sleeper" where he plans to clone a whole body just from the leader's nose, and then, right into the clothes he's laid out for him on the operating table!!
 
 
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MatPlus.Net Forum Retro/Math Promotions in the proof-game of an orthodox direct-mate