Author: Gian-Carlo Pascutto
Date: 00:52:45 12/11/00
Hi all,
My program has had trouble with getting back a best line from
its search since a long time. I decided to try to fix this and
have it working now, but I have a question on one of the changes
I had to introduce. I use a triangular system like e.g. TSCP does.
In the psuedocode below, which is the non-first move part of PVS:
value = -PrincipalVariation(depth-1, -alpha-1, -alpha);
if (value > alpha && value < beta)
best = -PrincipalVariation(depth-1, -beta, -value);
I will get truncated PV's. The way to fix this is to replace the
-value in the last call by -value+1. This is needed because the
first call can get a fail-high, and return an exact value if the
new best move is one unit better than the previous one (I use
fail-hard). The research will then fail low (score is equal to
alpha) and get a truncated PV.
Did I get this correct? Is there anybody else who had to do
something similar?
--
GCP
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