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Subject: More compact EGT information

Author: GuyHaworth

Date: 01:44:12 04/17/04

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Certainly, it should be possible to 'compact' an endgame's EGT information if
higher-level rules could be found.

These could preface the classic data-level EGT, providing sufficient information
 (whatever that means) without recourse to the EGT itself.

In some situations, maybe the following is possible:

a)  if your position is one of these, here is the value/depth
b1) otherwise, if conditions C11, ... C1,n1 apply, use Rule 1
b2) ...


An example in this vein is for the DTZ50 EGTs.  Marc Bourzutschky recently
observed that, if there are no 50-move affected subgames, we don't need a DTZ50
EGT separate from the DTZ EGT.  We just improve the DTZ50 probe-code
intelligence to understand that DTZ > 50 ==> draw.

This saves quite a bit, even though we plan to use an 'EdZ50Z' EGT in
association with a DTZ EGT, rather than a DTZ EGT and a DTZ50 EGT [because it's
only necessary to encode the difference between DTZ50 and DTZ.]


I have more than once thought that straight bit-level values ought to be useful
somewhere.  For example, after you know you have a win, you only need 0/1 for
'draw/win'.


Last thought is on compression.  Kadatch's scheme is good but maybe there are
more effective, more data-sensitive compression schemes.

I gather Eugene's index-regime uses a lot of RAM.  A more 'runtime' approach to
the maintenance of relevant indexes would I think save lots of RAM here.


g





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