Author: William Bryant
Date: 18:57:11 01/19/99
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On January 19, 1999 at 08:08:13, Robert Hyatt wrote: >On January 18, 1999 at 20:00:39, William Bryant wrote: > >>When a position is evaluated with a score that is > than alpha, that position >>then replaces alpha, and gets stored in the hash table as an EXACT score. >>If this move is the move backed up to PV[ply][ply], is the 'Best Move' that is >>stored in the hash record the move at PV[ply][ply + 1]; ie the next move to >>take from this position? > >easy answer. if search_value == beta, then the move to store is the current >move you just searched (in my case, current_move[ply]). If search_value is >> alpha and < beta, then you store the move in the pv[ply] array. If the >search_value is <= alpha, you have no best move to store. > > >> >>If it is, then when getting a hash table hit, with an appropriate draft, is the >>best move then used as the move to search next by returning it to the pv >>at the position PV[ply][ply + 1]? > > >when you do a hash probe and 'hit' you try the hash move first no matter what >is going on... > Thank you, but I'm still unclear on using the best move. You arrive at a new position, its hash signature matches an entry in the hash table whose draft is sufficient to make the score useful. You return this score rather than search this position further. BestMove is the next move to make from this position, but at present your are through searching this position as you already have a score which you may or may not use depending on the rest of the search. I suspect, the value of the best move is to guide the search when you are searching to a greater depth (the next iteration or so). The the best move is the move to search first from this position when searching to a greater depth (when the draft is insufficient) ie, when you go deeper, start with this move to try and produce early cutoff's. Am I close? Thanks. William wbryant@ix.netcom.com
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