# [Retros] Retros: Eternally winning position and 50moves rule YefimT 08/25/2004

Michael Niermann-Rossi mniermannrossi at yahoo.de
Thu Aug 26 03:07:29 EDT 2004

> FEN Notation (but please check it by algebraic notation below too):

> 1b6/2p5/1pP5/1P6/3p1p1p/2pP1P1K/2P1BP1p/7K w 0--1

Should be:
1b6/2p5/1pP5/1P6/3p1p1p/2pP1P1k/2P1BP1p/7K w - - 0 1
(bK on h3!!)

> Or: White:Kh1,Be2,pp:b5,c2,c6,d3,f2,f3

> Black: Kh3, Bb8,pp:b6,c3,c7,d4,f4,h2.h4 White to move.

> It is clearly, that if White does not deliver mate then game follows very

> simple eternally (suppose there was no 50 moves rule).

And no 3-fold repetition rule! It would apply first.
Or if black doesn't claim a draw.

> Now. I am offering the following. Eliminate the rule of 50 moves (by the

> way

> why 50 moves no more no less) and set up the following rule:

The reason is probably, that you need 35 moves for K+N+B vs. K and they
wanted to give some extra moves. So they chose the next "round" number (or
what people think to be round, I'd prefer 64 :) ). Of course this number
is randomly chosen and there are practical and artificial examples where
50 has been proven to be not enough. But the rules were made for chess as
a game, a competition for 2 players, not for chess problems, retro analysis
or mathematical modelling. Take it as an axiom.

IMO your point of view is wrong. You want to describe chess with a
mathematical model. You define a tree, but it doesn't describe chess
correctly. Then you start thinking about how to change the chess rules
to make it suitable to your tree instead of making corrections on your
tree.

I think a node of your tree should contain all the informations in FEN
without the move number, but also the following:
1) all positions since the last pawn advance or capture
2) the state of the game: 0 for "no draw offer, not finished", 1 for
"White offered draw", 2 for "Black offered draw", 3 for "Black
resigned", 4 for "White resigned", 5 for "draw agreed", 6 for
"stalemate", 7 for "mate", 8 for "draw claimed", 9 for "Black
lost on time", 10 for "White lost on time"
(I hope that's all...)

possible actions are now:
1) legal moves
2) resigning
3) offering a draw
4) accepting a draw offer
5) claiming a draw

the edges from a given position are given by these actions following
some rules. E.g. action 4) resulting in a pos. with state 5 is only
possible if the pos. has state 1 or 2
Or action 5) is only possible, if the 50-moves-rule or the 3-fold
repetition rule apply, which can be described by the number of halfmoves
given in FEN and the positions since the last pawn advance or capture.

OK, the number of halfmoves since the last pawn advance or capture has
not be part of the position, we should remove it, too... :)

If you now describe the edges correctly you'll get a mathematical model
of chess.

In your model you remove a lot. All aspects of competition have gone. But
then you may (and should) also remove the 50 moves rule etc., since it is
also made for competition. You get some similar game, but not chess.

Regards, Michael

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