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Subject: Re: start your engines ...

Author: Jonathan Kreuzer

Date: 09:49:49 03/10/04

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I'm think I understand you, and indeed not searching very far in winning lines
sounds like a good idea to me. (I've thought about this and other eval-based
'pruning', but never implemented any. Actually I'd consider null-move
eval-dependent pruning, but null-move is all I do.)

However it seems to me like you could do this in some form and still find mates
very quickly.

So on fail-high moves, you'd want them to fail high as fast as possible, hence
dropping extensions, etc. for the winning side.

However for the PV, if a human thinks a move is winning, he/she will probably
search even deeper along that line. When you've found a mate is when you have no
worries about a very deep refutation of the winning line. Actually now that I
think of it, I guess the reason for Gothmogs slowness declaring mate here is,
though searching the stronger initial move more deeply would find mate sooner,
it searchs non-mating follow up moves more deeply? I was initially confused by
the "make sure there isn't a very deep refutation of the (apparently) winning
line" because in this position using the time to declare mate once the crushing
move is found is the quickest way to do this, but in other positions it probably
isn't. So now that I've completely forgotten what either of us were talking
about, I'm done thinking about search, it's too confusing =)

PS. Though I haven't done much of it myself, I do think evaluation-directed
search (or knowledge-directed search) is the best way to go, and Gothmog is one
of the more interesting engines out there.



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