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Subject: Re the FIDE 50-move rule

Author: guy haworth

Date: 06:27:43 04/04/00

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When Eugene Nalimov started generating 6-man tables, he asked "what should we do
about the 50-move rule?"

Some said "nothing - ignore it - give us the absolute truth" and others said "do
something - we would like to win winnable games within the 50-move rule."

I have therefore proposed what should be done given that there is a 50-move
rule.  If the ICGA's current plan is achieved, this will be in the ICGA Jrnl.,
v23.1 (2000), probably being published in April.

The proposal does not stop the composition and 'absolute truth' communities (to
whom the 50-move rule does not apply) exploring the absolute capabilities of the
chess men.

The proposal DOES include a suggestion that a k-move rule should not apply to a
player who can clearly, effectively win a deep ending.  Since a rule along the
lines "the k-move rule does not apply to X if X has the endgame table" would be
technology-oriented and exclude other ways of winning effectively, there is an
interesting (and at this stage theoretical) discussion to be had about what
'sufficiently clearly' and 'sufficiently effectively' might be.

Is a player who takes 10% more moves than the optimal number (whatever that
might be, M-optimal, C-optimal ....) being 'sufficiently effective'?

The article goes on to show that players who play M-optimally or C-optimally may
not win games that should be won under the 50-move rule.  KNNKP provides one of
the examples.  Even Z-optimal play (minimising moves until the move-count is
zeroed by FIDE Article 9.3) may 'blow' a win.

The first examples of 'difficult' positions for which all the obvious minimax
strategies fail are likely to be found in KBBKNN and KQP(a6)KQ (and similar
pre-long-KQPKQ-phase) positions.

The article therefore defines the metric DTR or 'Depth By the Rule', this being
the smallest 'k' for which the (theoretically won) position would NOT be a
'draw' under a k-move rule.  Tables to the DTR metric can be generated and used
to effect, preferably in conjunction with (currently non-existent) tables to the
DTZ metric.

Guy



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