TalkChess.com

[Mike Adams]

hi,

I use check extensions in my program ( pulsar ) and i also hash. I turn on extensions at a variable depth, like once its searched the first 2 ply. this means pottentailly that if a depth like depth 6 is hashed and it was hashed on ply 2, before check extensions, it may not be the same deepeness of search as something searched on ply 3 to 6 depth when check extensions were on for one additional level. Is this a problem? How would you correct it? I know how deep i searched when i hash in terms of where i came from but dont offhand know how deep i searched after the depth i hashed from. Some lines would get searched deeper than others if there was check extensions activated. I'm thinking it shouldnt matter to much but wanted to get others opinions.

thanks
Mike

[H.G.Muller]

Always store the true depth to which a position is searched in the hash. When you retrieve it, you can judge if this depth is sufficient for the depth you want now, taking the extensions into account. You don't care if the entry in the hash was made in an extended 5-ply search or a non-extended 6-ply search, it is the same search and so it should lead to an identical entry.

If you worry about some sub-trees being searched deeper in some cases, you would really have to store that information in the hash table. Logically it is part of the depth information. A stored depth (draft) of 6 with extensions suppressed should not be able to satisfy a request for a search of depth 6 with extensions switched on ('depth 6+'), but the latter search should not be able to satisfy a request for a 7-ply search without extensions. It is really an intermediate depth.

[Onno Garms]

[Chan Rasjid]

Hello,

I think Muller's comment to just hash the actual depth to which a position is searched is normally sufficient in hashing and the rests will fall into proper perspectives.