# [Retros] Dead position with eternally moving Queen YefimT 08/26/2004

Michael Niermann-Rossi mniermannrossi at yahoo.de
Fri Aug 27 04:02:14 EDT 2004

--- doubleexclam at comcast.net schrieb:

> Let's talk rules as applied to chess PROBLEMS. The 3-move repetition and

> 50-move draws should not be so hastily discarded. They are clearly defined

> rules. The only change made for chess problems is that the draw is

> automatic; it does not need to be 'claimed' as in a game. The 50-move rule

> is honored even if the 'wrong' player has the move, i.e. he played the move

> rather than making the claim before the move, as would be proper in a game.

> There are examples (several retros by N. Plaksin) that make good use of the

> 50-move rule. I believe there are even Proof Games that use the 3-move

> repetition rule (composed by Buchanan, if memory serves).

I completely agree with you.

Some of the elements of the position may be unknown, in problems esp. retros
this may be an essential part. Given a set of positions (e.g. by not giving
the rights to castle) first you have to find out the possible positions (i.e.
to them there must be a path from the initial position). I think retro
problems in this model can be considered as problems of the type "Given a set
of positions by specifying only some of the variables, find out certain
values of the others (or at least some information on them) under the
condition that there is a path from the initial position.

And if the 50-moves or 3-fold repetition rule is part of a problem, you need
all these informations.

Of course we can change the rules for problems as you said, but then we have
different "possible actions" and therefore different possible edges, i.e. we
get a different definition of the tree.

> If we dispose of these rules because human players don't always claim them

> properly, then we should dispense with mate and stalemate and even legal

> moves for the same reason.

There is a slight difference: an illegal move must be discarded, even if it
is discovered later in a game. A missed claim has no effect like this.

regards, Michael

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