Author: Kim Roper Jensen
Date: 04:43:24 09/12/04
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On September 11, 2004 at 19:43:56, Stuart Cracraft wrote: >Hi, > >Added fractional extensions today and it boosted solution rate >a little more than 1% for the problem set. This was just a set >I threw in without much thought so that's pretty good considering >improvements lately have been hard to come by though the board >is helping to drive them a lot faster than if I were working it >alone. > >I initialize variable "extend" to 0.75 on entry to main search but I'll >probably make that 0 and the next number below a 1. I don't keep >track of the number of checks in a row but could to do the skip >so this isn't like Bob's. The 0.75 is just homage. >If in check, add 0.75. >If a recapture, add 0.75. >If a pawn extension, add 0.50 (this one is disabled presently but now > that fractional extensions are in, it and the other extensions I haven't > left enabled for fear of blowup can be all added in most likely.) >If extension total is >= 1.0, depth+=1 otherwise keep previous setting of depth. >... various non-extensions work here... test whether depth>=0 for > call to quiescence, null move with adaptive null move, etc. > (verified null move doesn't work as well for me for my short searches) >Generate moves, score, and sort >If only one legal move, give a free extension beyond the above. > >So, an example. If in check, extend by 1 (since 1.50 (0.75+0.75)). >If in check and this node is after a recapture extend by 1 (0.75+0.75+0.75>=1) >If in check and only one legal move out extend null move by 1 but then > 1-N moves by 2 (0.75+0.75>=1 + one legal move (1)) > >I was surprised to get a jump like this on the first attempt addition >of the fractional extension feature. 99/100 times a new thing added drops >solution rate slightly or more rarely by a lot. > >with fractional extensions >+ 6.19/24.31 82% 246/300 249.13 58736604 195789/1/235770 0/639780/1159759/415210 >/12993546/0 >pawnx/recapx/qcheckx/checkx/futilx/onereplyx >Missed: >2 21 46 71 80 86 87 92 99 100 116 128 131 141 145 155 163 178 180 196 200 210 21 >3 214 221 222 223 226 228 229 230 237 241 243 245 247 252 255 256 261 262 265 26 >6 269 274 282 283 287 288 291 293 296 297 299 >branching factor = 4.06 > >before fractional extensions >+ 6.37/23.52 80% 242/300 248.87 58082496 193608/1/233381 0/640257/1159613/384586 >/13051686/0 >pawnx/recapx/qcheckx/checkx/futilx/onereplyx >Missed: >2 21 49 55 71 80 86 87 92 97 99 100 116 128 131 139 141 145 155 163 180 196 200 >207 210 213 221 222 223 226 228 229 230 231 237 241 243 245 247 250 252 255 256 >260 261 262 265 269 274 282 283 287 288 291 293 296 297 299 >branching factor = 3.81 > >qcheckx refers to evading checks in the quiescence. This is just a measure >of the handoffs to the main search from a quiescence that is entered in >check, using depth=1 -- in these cases, the check extension in the main >search is disabled and not used since it already received an extra ply >from the handoff. > >Curious what are all the different fractional extensions people are using >for the various types of extensions. > >Now's your chance to write all of yours in here. E-X-T-E-N-D yourself! > >Stuart Hi Stuart Being a not so good programmer myself with a very nonfunctional program I just remembered someone mentioned sometime ago doing negative extensions also for reducing tree size /kim
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