Author: Robert Hyatt
Date: 11:30:15 08/20/01
Go up one level in this thread
On August 20, 2001 at 11:56:35, José Carlos wrote: >On August 20, 2001 at 09:43:22, Robert Hyatt wrote: > >>On August 20, 2001 at 05:22:36, Gian-Carlo Pascutto wrote: >> >>>On August 20, 2001 at 04:41:41, José Carlos wrote: >>> >>>> Then I tried not doing it in the PV, and the strange things went out. The tree >>>>got smaller and the search deeper. >>>> I don't know if this is the correct way of doing it (never do a null-move in >>>>the PV), cause I like to try myself before looking other's sources to see how >>>>they do it. But looks reasonable. In the PV, we don't expect to fail high, so >>>>why trying a null move? >>> >>>I don't do this, and crafty doesn't seem to be doing this either. >>> >>>However, your explanation makes perfect sense and I will try it. >>> >>>-- >>>GCP >> >> >>I used to do it but I found that trying nulls _everywhere_ actually made my >>tree smaller. I do it this way now because it was more efficient when I >>tested it.. Not by a lot, but better. > > Mmm, some time ago I asked about my not enough deep search, and some of you >pointed me to the move ordering. I found that null moves in the PV caused the PV >to go crazy sometimes. So I stoped doint null moves in the PV (according to my >previous post reasoning) and I did the trick. My fail high on the first >move/fail highs rate moved from 86-92% to 90-96%. And my search went to 'normal >depths'. Now I doubt again... Is there something I have to take into account >when doing null moves in the PV to avoid getting strange PV's? I know, the >question is too vague but, maybe someone has an idea. > So, everyone does null moves in the PV? > > José C. I don't see how nulls on the PV can cause "strange PVs". If you have a position that drives your search nuts, post it and I will run it with Crafty with null on and off to see how it behaves. Null-move definitely causes quirks here and there, particularly false fail highs if you use PVS and you have to handle them correctly or blow up.
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