Author: Anthony Cozzie
Date: 19:18:04 12/28/03
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On December 28, 2003 at 13:32:05, Tom Likens wrote: >Hello Everyone, > >I've been experimenting recently with using the evaluation function to shape >the search tree. Specifically, I've been using the static evaluation of >the current position and the previous position to determine if a move should >be extended or reduced. I also have been making allowances for moves that >increase or decrease the pressure against the king, attack hung pieces, >save hung pieces etc. > >So far the results have been exciting, but also potentially frustrating. >The main problem I've encountered is that any pruning or extensions based on >the previous node's score cause hashing problems because this becomes path >dependent. In a way, I suppose this isn't much different then making these >type of decisions based on the value of alpha or beta as well, but these new >effects have (at least for my program) seemed more detrimental. > >My (obvious) question, how do other programmers deal with this phenomenon? >I suppose ignoring it is one option, but I'm hoping there is a better >solution. > >regards, >--tom In my personal opinion: The time of such static tricks has passed. When people ran on a 386 and struggled to get 5 ply, extensions && pruning were critical. Top programs nowadays get 14 ply. The simple fact of the matter is that computers are almost perfect tactically. More depth now is purely for positional benefit. Right now I'm trying to _reduce_ my extensions, not add more :) Thorsten and Ed have both said that Rebel plays better with the reductions off. The only engine on ICC that uses his reductions is Chompster, and I've seen chompster make errors on a 10 ply search that Zappa catches with a 6 ply search. That all said, your time is your own to spend :) anthony
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