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Subject: Question About Hash Table Contents Optimization

Author: Bob Durrett

Date: 09:15:55 06/17/03



This question is in the context of exhaustive post-mortem analysis of games,
using a chess engine.  [I use Fritz.]

Typically, a chess engine in automatic analysis mode will begin analysis with
the last move of the game and then progress eventually to the point where
opening book moves are made, whereupon automatic analysis is terminated.
Presumably, this back to front method helps to make sure relevant/useful
information is in the hash tables at all times during the automatic analysis.

Similarly, if a given position in the game is analyzed, the chess engine will
give a line for that position.  Usually, if the human operator subsequently
makes the engine examine the last move of such a line, the evaluation will be
quite different.  As the operator steps backwards from the end of the line
toward it's beginning, often it happens that improvements are found.  It is not
uncommon for the second move in the line to be in need of improvement.

This begs the question as to what is happening to the contents of the hash table
during such processes.  More importantly, there may be an optimal procedure
which will optimize hash table contents so that the overall analysis products
are optimized.  How best to do that is the question.

My procedure, which I suspect to be common, is to first let the engine analyze
the game overnight.  Then I look at the resulting analysis, again progressing
from last move to first move, marking positions I wish to examine more.  I call
this "pre-analysis."  Maybe I should stop here, to avoid boring anybody, since
everybody here has done the same thing.  No need to elaborate.

How should one proceed, in post-mortem analyses with chess engine assistance, to
get the very best overall analysis results?  I suspect that this would depend on
using methods which optimize hash table contents.

Anybody wishing to shed light on this topic will become my "instant hero."  : )

Bob D.




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