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Date: 12 Dec 2007 00:44:36
From: Proginoskes
Subject: Retrograde analysis and the 50-move rule
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One type of retrograde analysis problem is determining whether a
particular set-up of the pieces can arise from a legitimate game.
Sometimes it can be shown that a position is "impossible" because a
piece (usually a bishop) had to get out from its original square, but
the only possible exits are blocked.
I got to thinking about "proofs of impossibility" and I wondered: Is
there a position which can be proven to be impossible, because the 50-
move rule was violated?
If all the pieces are on the board, that shows that a capture has not
been made, but how would you show that a pawn hasn't been moved in the
past 50 moves? It seems like it might be impossible, so I decided to
let some people know about the problem.
--- Christopher Heckman
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Date: 13 Dec 2007 23:14:24
From: Proginoskes
Subject: Re: Retrograde analysis and the 50-move rule
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On Dec 13, 10:38 am, mrmip <[email protected] > wrote:
> > Could it be this one?
>
> >http://homepage.ntlworld.com/gpjnow/VC-GP.htm#F
>
> That is the Breyer all right!
I'll have to think about this for a moment. My first thought was: Why
couldn't Black's last move have been Kd7-d6, after White played fxe6+
(taking some Black piece on e6)? Presumably this gets ruled out when
you go farther back ...
> There are plenty of retroproblems, where
> 50-move rule plays a central role. Nikita Plaksin alone composed 50
> such problems. Famous 50x50 by Plaksin are to be found in PDB-
> database.
http://www.softdecc.com/pdb/index.pdb
> But to return to original question:
>
> "I got to thinking about "proofs of impossibility" and I wondered: Is
> there a position which can be proven to be impossible, because the
> 50-
> move rule was violated?"
>
> I would say no, there is no such position. 50-move rule never makes a
> position impossible only gives a right to demand a draw (which is not
> obligatory -only an option).
Several people have called me on this. Yes, it's a privilege, not a
obligation.
--- Christopher Heckman
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Date: 13 Dec 2007 14:16:11
From: help bot
Subject: Re: Retrograde analysis and the 50-move rule
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On Dec 12, 3:44 am, Proginoskes <[email protected] > wrote:
> One type of retrograde analysis problem is determining whether a
> particular set-up of the pieces can arise from a legitimate game.
> Sometimes it can be shown that a position is "impossible" because a
> piece (usually a bishop) had to get out from its original square, but
> the only possible exits are blocked.
>
> I got to thinking about "proofs of impossibility" and I wondered: Is
> there a position which can be proven to be impossible, because the 50-
> move rule was violated?
You demonstrate a misunderstanding of what the
50-moves rule is; it is impossible to "violate" this
rule; moreover, claims of a draw by the 50-moves
rule are entirely optional, so the above discussion
wrongly assumes that claims are automatic. In
fact, it is possible that neither side wants to claim
a draw, even if losing on the board.
-- help bot
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Date: 13 Dec 2007 09:38:02
From: mrmip
Subject: Re: Retrograde analysis and the 50-move rule
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>
> Could it be this one?
>
> http://homepage.ntlworld.com/gpjnow/VC-GP.htm#F
>
> --
> Anders Thulin anders*thulin.name http://www.anders.thulin.name/
That is the Breyer all right! There are plenty of retroproblems, where
50-move rule plays a central role. Nikita Plaksin alone composed 50
such problems. Famous 50x50 by Plaksin are to be found in PDB-
database.
But to return to original question:
"I got to thinking about "proofs of impossibility" and I wondered: Is
there a position which can be proven to be impossible, because the
50-
move rule was violated?"
I would say no, there is no such position. 50-move rule never makes a
position impossible only gives a right to demand a draw (which is not
obligatory -only an option).
mrmip
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Date: 13 Dec 2007 02:33:25
From:
Subject: Re: Retrograde analysis and the 50-move rule
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Proginoskes wrote:
> One type of retrograde analysis problem is determining whether a
> particular set-up of the pieces can arise from a legitimate game.
> Sometimes it can be shown that a position is "impossible" because a
> piece (usually a bishop) had to get out from its original square, but
> the only possible exits are blocked.
>
> I got to thinking about "proofs of impossibility" and I wondered: Is
> there a position which can be proven to be impossible, because the 50-
> move rule was violated?
>
> If all the pieces are on the board, that shows that a capture has not
> been made, but how would you show that a pawn hasn't been moved in the
> past 50 moves? It seems like it might be impossible, so I decided to
> let some people know about the problem.
>
> --- Christopher Heckman
According to Reti (Modern Ideas in Chess, ch. 34), Breyer composed
such a problem, though I've never seen it. (To be precise, the passage
could be read to mean that Breyer edited the magazine in which the
composition appeared, without composing it himself.) Has anyone seen
the problem?
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Date: 13 Dec 2007 16:18:57
From: Anders Thulin
Subject: Re: Retrograde analysis and the 50-move rule
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[email protected] wrote:
> According to Reti (Modern Ideas in Chess, ch. 34), Breyer composed
> such a problem, though I've never seen it. (To be precise, the passage
> could be read to mean that Breyer edited the magazine in which the
> composition appeared, without composing it himself.) Has anyone seen
> the problem?
Could it be this one?
http://homepage.ntlworld.com/gpjnow/VC-GP.htm#F
--
Anders Thulin anders*thulin.name http://www.anders.thulin.name/
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Date: 13 Dec 2007 01:30:03
From: Proginoskes
Subject: Re: Retrograde analysis and the 50-move rule
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On Dec 12, 4:56 am, "Chess One" <[email protected] > wrote:
> "Proginoskes" <[email protected]> wrote in messagenews:3d72a550-7db8-4913-b2e3-eb8ca4cd1da0@d27g2000prf.googlegroups.com...
>
> > One type of retrograde analysis problem is determining whether a
> > particular set-up of the pieces can arise from a legitimate game.
> > Sometimes it can be shown that a position is "impossible" because a
> > piece (usually a bishop) had to get out from its original square, but
> > the only possible exits are blocked.
>
> > I got to thinking about "proofs of impossibility" and I wondered: Is
> > there a position which can be proven to be impossible, because the 50-
> > move rule was violated?
>
> Yes. Set up a mate with White; K, B, B, and Black; K. Regress the game to a
> Kling & Horwitz fortress, awarding black a N along the way,
This isn't quite what a retrograde anaylsis problem is.
Suppose you have a chessboard where White has pawns on a2, b2,
c2, ..., h2, and a bishop on e3 (the places of other pieces are
immaterial). Now this position could not possibly have arisen from the
original setup, because in order for the bishop to have gotten out,
one of the pawns on b2 or d2 would have to have been moved (and these
haven't); or the bishop is a promoted pawn (but this is also
impossible, since all 8 pawns are still on the board).
If you have only the position with K+B+B vs K mate, you don't know
that the position arose from a K&H fortress. In particular, there's no
way to prove that White's last move COULDN'T have been bishop takes a
piece (delivering mate), in which case the 50-move rule wasn't
violated after all.
--- Christopher Heckman
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Date: 13 Dec 2007 10:12:52
From: Chess One
Subject: Re: Retrograde analysis and the 50-move rule
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"Proginoskes" <[email protected] > wrote in message
news:05316ad0-482e-4e70-b46a-aecdf015c5ac@a35g2000prf.googlegroups.com...
> On Dec 12, 4:56 am, "Chess One" <[email protected]> wrote:
>> "Proginoskes" <[email protected]> wrote in
>> messagenews:3d72a550-7db8-4913-b2e3-eb8ca4cd1da0@d27g2000prf.googlegroups.com...
>>
>> > One type of retrograde analysis problem is determining whether a
>> > particular set-up of the pieces can arise from a legitimate game.
>> > Sometimes it can be shown that a position is "impossible" because a
>> > piece (usually a bishop) had to get out from its original square, but
>> > the only possible exits are blocked.
>>
>> > I got to thinking about "proofs of impossibility" and I wondered: Is
>> > there a position which can be proven to be impossible, because the 50-
>> > move rule was violated?
>>
>> Yes. Set up a mate with White; K, B, B, and Black; K. Regress the game to
>> a
>> Kling & Horwitz fortress, awarding black a N along the way,
>
> This isn't quite what a retrograde anaylsis problem is.
>
> Suppose you have a chessboard where White has pawns on a2, b2,
> c2, ..., h2, and a bishop on e3 (the places of other pieces are
> immaterial). Now this position could not possibly have arisen from the
> original setup, because in order for the bishop to have gotten out,
> one of the pawns on b2 or d2 would have to have been moved (and these
> haven't); or the bishop is a promoted pawn (but this is also
> impossible, since all 8 pawns are still on the board).
>
> If you have only the position with K+B+B vs K mate, you don't know
> that the position arose from a K&H fortress. In particular, there's no
> way to prove that White's last move COULDN'T have been bishop takes a
> piece (delivering mate), in which case the 50-move rule wasn't
> violated after all.
You are right, but I thought I was responding to a different problem, to
show any 50+ move retrograde sequence where with best play a draw might be
claimed? If there was another condition, that is, the 'forcing' sequence
needs to accomodate capture of *any* piece, I did not take that into
account.
But I see I am wrong for another reason, since after the Knight capture
White mates quicker than 50 moves against the bare King. Phil Innes
> --- Christopher Heckman
>
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Date: 12 Dec 2007 06:56:33
From: Chess One
Subject: Re: Retrograde analysis and the 50-move rule
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"Proginoskes" <[email protected] > wrote in message
news:3d72a550-7db8-4913-b2e3-eb8ca4cd1da0@d27g2000prf.googlegroups.com...
>
> One type of retrograde analysis problem is determining whether a
> particular set-up of the pieces can arise from a legitimate game.
> Sometimes it can be shown that a position is "impossible" because a
> piece (usually a bishop) had to get out from its original square, but
> the only possible exits are blocked.
>
> I got to thinking about "proofs of impossibility" and I wondered: Is
> there a position which can be proven to be impossible, because the 50-
> move rule was violated?
Yes. Set up a mate with White; K, B, B, and Black; K. Regress the game to a
Kling & Horwitz fortress, awarding black a N along the way, so that you
reach :Black, Ke5, Ne4.
If you do this with a computer then set 'Fritz' with search greater than 15,
otherwise the N escapes!
Good luck! BTW, not all Kling & Horwitz fortresses are solved, and the Ke5,
Ne4 position above is not necessarily the longest forced start position.
If you don't use computer, beware! previous attempts to solve the fortress
above went 150 years with no result. I think [!?] - this is a 55-move
string, it may not be the longest.
I would be most interested if you can 'solve' this question by retrograde
action!
Phil Innes
> If all the pieces are on the board, that shows that a capture has not
> been made, but how would you show that a pawn hasn't been moved in the
> past 50 moves? It seems like it might be impossible, so I decided to
> let some people know about the problem.
>
> --- Christopher Heckman
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