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Subject: EGT-access module - and runtime EGT-generation

Author: GuyHaworth

Date: 00:43:53 11/23/05

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Certainly, the function of accessing whatever portfolio of EGTs were available
is separate from:

  - the core search-engine's function, and
  - the function of accessing an individual EGT-type and EGT

Therefore, it should be functionally separate in the software architecture.

One could therefore imagine this module evolving behind defined interfaces, but
quite independently of the FRITZ, FRUIT, JUNIOR, SHREDDER etc developments.

Such a module might have access to EGTs of varied format and metric:

  - deKoenig (FEG), Nalimov (most promulgated), Konoval (to come)
  - DTC(onversion), DTM(ate) (Nalimov), DTZ (most compact), WDL (bit-pair map)


Further, such a module might be more dynamic at runtime.  EGTs are consuming
many GBytes now, and there is an argument now for saving space and using time as
and when required instead ...

EGTs can be 'cut back' to hold, say, only the draws, broken positions and
wins/losses 0 and 1 moves from the game/subgame boundary.  It could then be
reconstructed more rapidly because the draws are known and there are no required
references to subgames.

Reconstructing the EGT would be an integral part of 'forward search', done
differently when it was known that definitive data could be 'backed up' to
evaluate the position.

The speed demonstrated by Yakov Konoval's program, not yet parallelised, shows
that this could be done at runtime within a game for 5-man positions and some
6-man.  The potential use of FREEZER within-game is also possible, and maybe
SHREDDER is there already.  6-man positions with a pair of blocked-pawns are
effectively 4-man EGT-generations with 5-man EGT lookup.

How long it would take would depend on the depth of the position to be analysed
in the game.  Although DTx-graphs often have long tails, average depths are
usually much less than maxDTx.


Incidentally, this would raise an interesting philosophical question for
man-machine matches where the carbon side objects to the silicon having access
to N-man EGTs.  "No, we have no N-man EGTs - but we do have the ability to
create them as a legitimate part of the search function."

g






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