Author: Robert Hyatt
Date: 11:43:16 01/13/98
Go up one level in this thread
On January 13, 1998 at 09:08:49, Dan Homan wrote: >On January 12, 1998 at 14:49:17, Robert Hyatt wrote: > >>On January 12, 1998 at 14:23:02, Dan Homan wrote: >> >>>Test Position: WAC 003 >>> >>> +---+---+---+---+---+---+---+---+ >>>8 | | | | | | *R| *K| | White to move >>> +---+---+---+---+---+---+---+---+ >>>7 | | *P| *P| *B| | | | *P| castle: - >>> +---+---+---+---+---+---+---+---+ >>>6 | *P| | *P| *B| | | | | >>> +---+---+---+---+---+---+---+---+ >>>5 | | | | | | | *Q| | >>> +---+---+---+---+---+---+---+---+ >>>4 | | | | P | | *P| | *R| fifty: 0 >>> +---+---+---+---+---+---+---+---+ >>>3 | | | P | | R | | | P | >>> +---+---+---+---+---+---+---+---+ >>>2 | P | P | | B | Q | | P | | >>> +---+---+---+---+---+---+---+---+ >>>1 | | | | | | R | K | N | >>> +---+---+---+---+---+---+---+---+ >>> a b c d e f g h >>> >>> >>>White to Move Book Move: Rg3; >>> >>>Press 's' to search, 'n' for the next position, 'q' to exit: s >>>Please enter a search time (in seconds): 30 >>> 3. 154 0 1300 e3g3 g5g3 h1g3 >>> 4. 313 0 5297 e3g3 d7g4 g3g4 >>> 5. 313 0 10408 e3g3 d7g4 g3g4 >>> 6. 313 2 53982 e3g3 d7g4 g3g4 >>> 7. 313 5 174534 e3g3 d7g4 g3g4 >>> 8. 313 20 735301 e3g3 d7g4 g3g4 h4g4 e2e6 g8h8 >>> h3g4 g5f6 f1e1 f4f3 >>> >>>node_count = 885911 quiescent nodes = 82048 eval_count = 183571 >>>hash hits = 74864 hash moves = 9095 pawn hash hits = 173696 >>>node_rate = 36912 null cutoffs = 167276 extensions = 15099 >>> >> >>I tried this to a depth of 8 plies (which I assume the above means >>you reached?) Total time was 2 seconds, with a hash hit rate of 99%. >>I re-ran it to 30 seconds and was able to search 11 plies deep this >>time, and the pawn hash hit rate was still 99%. I used 5mb for the >>pawn hash, where one entry is 20 bytes. >> > >I was just looking at these numbers and noticed that you are reaching >depth 8 in just 2 seconds! It takes me 20 to reach depth 8 (time to >complete the first PV on depth 8, the rest of the moves at depth 8 >take still more time). This is a factor of 10! Even assmuning a >generous factor of 3 in nps advantage, crafty is searching about a >factor of 3 fewer nodes! > >I can think of a few reasons that my search would have more nodes, but >none of them should be a factor of 3. One thing that did occur to me >is extensions. I turned off all extensions and researched this >position. In doing so, I found that I searched only about 30% of the >nodes to reach the same depth as the above example. Should my >extensions really be tripling the size of my search tree? > >I like the extensions a lot, just adding them in has increased my >program's blitz rating on FICS by 200 points (now about 2030). I am >wondering, however, if I have overdone it. What do you typically >expect the increase in tree size to be with reasonable extensions? > > - Dan > >p.s. My program does > >capture extensions (4/10 of a ply) dangerous one there. Ken Thompson used 1/2 ply in 1983, and probably lost the 1983 World Championship as a result of doing this. He reported it helped his WAC results quite a bit, but it costs about 1/2 to 1 ply. He later discarded it totally. >re-capture extensions (1 ply) >check extensions (1 ply) >pawn push extensions (1/2 ply or 1/3 ply) (endgame and late >middle-game) >bruce's mate ext. (1 ply) All reasonable. I am now using 3/4 ply for *everything* in Crafty, but do allow multiple extensions to add together, with a limit of 1 ply. This actually improved the WAC results and seems to be running a good bit faster to reach the same depth...
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