Computer Chess Club Archives




Subject: new thoughts on verified null move

Author: scott farrell

Date: 05:11:37 11/23/02

Just after other people's thoughts.

I think Omid's work overlooked the adapative null move searching many of us do,
ie. transitioning from r=3 to r=2.

I think adaptive null move tries to GUESS where to use r=2 to reduce the errors
that R=3 makes. I guess it depends on how often this GUESS is correct, the cost
of the verification search, and how long it takes the adaptive searching to
catch the error at the next ply.

Has anyone looked at setting the verification search to reduced depth of 2
(rather than 1)? obviously to reduce the cost of the verification search.

Robert : How did your crafty implmentation go?

I know that measuring nodes for a fixed search depth sounds like good science,
but I think you really need to look at where one method makes a mistake, and how
quickly it can find the mistake at the next ply. Obviously my point is if it
finds a given move with less nodes, thats good, if it takes an extra ply of
search, sometimes that's acceptable if we can catch it quick enough. We've all
seen how quickly at the next ply a fail low is often fast, well that is my major
"verification search" for ALL search problems - horizon, null move, etc etc. I
think it might be better to include some nodes from the next iteration, where
the next ply fails low really really quickly, and finds the mistake anyway,
maybe consider the nodes as part of the previous ply.


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