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Old June 11th 04, 04:02 PM
Harold Buck
 
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Default Longest Possible Chess Game !

In article ,
Antonio Torrecillas wrote:

but I remember there are some positions where it's needed more than 50
moves to win the game and those positions are considered excepcions to
50 moves rule in FIDE chess rules. Maybe if we arrive to an ending of
that kind the game can be longer.



IIRC, that rule has been eliminated. There used to be special endings
that allowed you 75 moves, I think, but as computers have "solved" more
and more endings, they decided to just make it 50 moves and if your
ending is winnable but takes 51 moves, too bad for you.

--Harold Buck


"I used to rock and roll all night,
and party every day.
Then it was every other day. . . ."
-Homer J. Simpson
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Old June 11th 04, 05:21 PM
Harold Buck
 
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Default Longest Possible Chess Game !

In article ,
Joost de Heer wrote:

Even if all the four knights move to every possible position twice and
nothing else moves there will probably be more than one hundred
combinations.
Then one pawn moves and the entire process starts again and so on.


You'll get crushed by the 50 move rule before you've done all permutations.



Huh? The count starts over with each pawn advance or capture. I think
the baseline calculation is [(16 pawns x 6 advances each) + (30 pieces
to capture)] x 50 moves between each pawn advance or capture = 6300
moves.

But this is a bit too much, since SOME of the pawn advances have to be
captures as well.

--Harold Buck


"I used to rock and roll all night,
and party every day.
Then it was every other day. . . ."
-Homer J. Simpson
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Old June 12th 04, 08:11 PM
Andrew Bull
 
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Default Longest Possible Chess Game !

Joost de Heer wrote in message ...
Even if all the four knights move to every possible position twice and
nothing else moves there will probably be more than one hundred

combinations.
Then one pawn moves and the entire process starts again and so on.


You'll get crushed by the 50 move rule before you've done all permutations.



So what's the longest possible game if you drop the 50-move rule but abide
by the threefold repetition rule? I suspect one can't do better than
estimate the answer to that...


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Old June 13th 04, 01:55 AM
Sam Sloan
 
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Default Longest Possible Chess Game !

On Fri, 11 Jun 2004 16:04:41 +0000 (UTC), Joost de Heer
wrote:

Even if all the four knights move to every possible position twice and
nothing else moves there will probably be more than one hundred combinations.
Then one pawn moves and the entire process starts again and so on.


You'll get crushed by the 50 move rule before you've done all permutations.

Joost
--


Good point ! Thank you very much.

OK. You make 49 moves with just the knights. Then you move one pawn.
Then you make another 49 moves with just the knights. Then you move
another pawn.

From the initial position there can be 32 pawn moves with no captures.
Therefore, we have 1500 moves.

Also, once a single pawn moves, other pieces can move too.

However, I am beginning to see the point. Maybe he is right and I am
wrong.

Sam Sloan
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Old June 15th 04, 02:48 AM
Harold Buck
 
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Default Longest Possible Chess Game !

In article [email protected],
"Ricardo Gibert" wrote:

Duplicates+ Drawing_interval_grace_period) * Drawing_interval, or


I don't understand what the "...Drawing_interval_grace_period.." means.



My guess is that it refers to the fact that the kings can shuffle around
for another 50 moves after all of the other pieces are gone. But if one
side were intent on claiming a draw, they could do so at this point, so
maybe the answer should be 5900?

--Harold Buck


"I used to rock and roll all night,
and party every day.
Then it was every other day. . . ."
-Homer J. Simpson
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Old June 15th 04, 08:56 AM
Guy Macon
 
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Default Longest Possible Chess Game !


Harold Buck says...

My guess is that it refers to the fact that the kings can shuffle around
for another 50 moves after all of the other pieces are gone. But if one
side were intent on claiming a draw, they could do so at this point, so
maybe the answer should be 5900?


Here are my calculations:

Assumptions:

[1] FIDE rules.

[2] Players cooperate in order to lengthen game.

[3] When a player can claim a draw (50 moves, repeated position, lack
of mating material, etc.) he does so, but tries to avoid positions
where either side wins or can claim a draw.

Start with 32 chesspieces.

Move 100 plies, avoiding repeating positions.

On ply 100, move a pawn or make a capture.

Repeat N times until you make the last capture that leaves 2 kings.

There are 30 100-ply sequences ending with a capture.

There are 96 100-ply sequences ending with a pawn move.

8 of these sequences end with a pawn move that is also a capture.

1 of these sequences is only 99 plies to so that black can start
taking his turn making captures.

Assuming FIDE rules, that comes to a total of no more than
(100*(30+96-8))-1)=11799 plies (5899.5 moves) until the game
is over. At 2 minutes per move that's 393.3 hours or 16.4 days.

The longest game may be shorter than this (I don't think it is)
but cannot be longer than this.

--------------------------------------------------------------

Here is one way it could happen:

(Assume 99 "wasted" plies between each step)

White advances his A,C,E,G pawns as far as they will go.

Black advances his B,D,F,H pawns as far as they will go.

White captures every black piece except 8 pawns, 4 other pieces,
and a King.

The A,C,E,G white pawns capture the 4 other pieces, thus passing
and freeing the A,C,E,G black pawns that were blocking them.

The now-unblocked A,C,E,G black pawns move forward, promote, and
the pieces they promote to move into position to be taken by the
white pawns on B,D,F,H, unblocking the B,D,F,H black pawns.

The now-unblocked B,D,F,H black pawns move forward, promote,
and are taken.

Black now only has a king. (Here is the lone 99 ply sequence) The
black king captures something, and the game continues with pawn
moves or captures by black on every 100th ply until there are only
two kings left - a draw.


--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
have an "impossible" engineering project that only someone like
Doc Brown can solve? My resume is at http://www.guymacon.com/

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Old June 15th 04, 03:36 PM
Harold Buck
 
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Default Longest Possible Chess Game !

In article ,
Guy Macon http://www.guymacon.com wrote:


Assuming FIDE rules, that comes to a total of no more than
(100*(30+96-8))-1)=11799 plies (5899.5 moves) until the game
is over. At 2 minutes per move that's 393.3 hours or 16.4 days.



I think this corresponds to the answer in the FAQ, which was 5950 moves,
except for two things:

1) I think they are "rounding up" so they don't have half-moves in their
answer.

2) I think they're allowing the kings to go 50 moves on an otherwise
bare board, which as someone pointed out is not allowed under FIDE rules.

--Harold Buck


"I used to rock and roll all night,
and party every day.
Then it was every other day. . . ."
-Homer J. Simpson
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