Author: Robert Hyatt
Date: 11:51:35 09/20/99
Go up one level in this thread
On September 20, 1999 at 14:08:26, Jon Dart wrote: >Arasan doesn't generate rook or bishop underpromotions except at >ply 0 (I think Crafty does the same thing). No. Crafty generates all promotions in normal search, but only generates queen promotions in the q-search. I think leaving out underpromotions is a mistake in the regular search... but in the q-search only doing queens seems reasonable if you don't handle checks and escaping from check. If you do, I'd likely throw in knight promotions... > >Forward pruning is a reasonable thing to do. In the qsearch, I >do something like: > >if (current material + gain from promotion + some constant < alpha) > skip move > >My latest build has this output on your example: > >ply 4. Kh3 0 seconds. score: -7.19 215 nodes. >ply 5. Kh3 0 seconds. score: -7.19 283 nodes. >ply 5. Kh3 0 seconds. score: -11.08 470 nodes. >ply 6. Kh3 0 seconds. score: -11.08 1144 nodes. >ply 7. Kh3 0 seconds. score: -11.11 2538 nodes. >ply 8. Kh3 0 seconds. score: -11.28 4856 nodes. >ply 9. Kh3 0 seconds. score: -11.28 5172 nodes. >ply 9. Kh3 0 seconds. score: -17.02 9453 nodes. >ply 10. Kh3 0 seconds. score: -17.52 19403 nodes. >ply 11. Kh3 0 seconds. score: -17.52 20700 nodes. >ply 11. Kh3 0 seconds. score: -156.00 50050 nodes. > >--Jon > >On September 20, 1999 at 02:09:30, Steffen Jakob wrote: > >>Hi all! > >> >>I still try to improve the playing skill of Hossa in pawn endgames (which is not >>very difficult because he plays them very badly). About underpromotions: I know >>that Amir Ban doesn't generate underpromotions in the search tree. I don't like >>that very much. What I am doing now is to reduce the search depth for >>underpromotions (one ply). It helps a lot in some positions, e.g. in the pawn >>endgame position where crafty saw that mate in 4 although it is a mate in 6. As >>you can see below I need 158616 nodes to see the mate without pruning and 135713 >>with underpromotion pruning. I think about reducing the depth by two plies for >>bishop underpromotions (can someone please give me some positions where the >>winner move is to promote the pawn to a bishop?). What are you thinking about >>this? Are there other ways to prune underpromotions? E.g. if you are sure that >>queen promotions are searched before underpromotions and alpha > xxx then it >>might be useless to try those moves (at least rook and bishop promotions). >> >>analysis without forward pruning: >>--------------------------------- >> >> +---+---+---+---+---+---+---+---+ >>8 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ Black: Hossa v1.63 (C) (0) >>7 ||P|| | | | | | | | >> +---+---+---+---+---+---+---+---+ Black material: 4 >>6 | P | | | | | ||P|| | >> +---+---+---+---+---+---+---+---+ >>5 | | | | | | | ||P|| >> +---+---+---+---+---+---+---+---+ White to move >>4 | | | | | | | | P | >> +---+---+---+---+---+---+---+---+ 8/p7/P5p1/7p/7P/4kpK1/8/8 w >>3 | | | | ||K|||P|| K | | >> +---+---+---+---+---+---+---+---+ White material: 2 >>2 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ White: opponent (0) >>1 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> a b c d e f g h >> >> >> depth value time nodes pv >> 1 -5.23 0.00 2 1.g3h3 >> <1> -5.23 0.00 3 1.g3h3 >> 2 -5.35 0.00 38 1.g3h3 f2 2.h3g2 >> <2> -5.35 0.00 48 1.g3h3 f2 2.h3g2 >> 3 -5.37 0.00 84 1.g3h3 f2 2.h3g2 e3e2 >> <3> -5.37 0.00 90 1.g3h3 f2 2.h3g2 e3e2 >>? 4 -510.92 0.01 194 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >>? <4> -510.92 0.01 207 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 5 -510.92 0.01 322 1.g3h3 f2 2.h3g2 >> <5> -510.92 0.01 335 1.g3h3 f2 2.h3g2 >> 6 -510.92 0.01 531 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> <6> -510.92 0.01 552 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 7 -510.92 0.02 1182 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 f2f1Q >> 4.h2g3 >> <7> -510.92 0.02 1203 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 f2f1Q >> 4.h2g3 >> 8 -510.98 0.05 2817 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 e2f3 >> 4.h2h3 f2f1Q 5.h3h2 >> <8> -510.98 0.05 2867 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 e2f3 >> 4.h2h3 f2f1Q 5.h3h2 >> 9 -510.97 0.09 5587 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 f1f2 5.h2h3 e2f3 >> <9> -510.97 0.09 5644 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 f1f2 5.h2h3 e2f3 >>? 10 -512.01 0.24 14405 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 >>? <10> -512.01 0.24 14556 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 >> 11 -512.03 0.64 41493 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 6.g3g2 >> <11> -512.03 0.65 41840 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 6.g3g2 >>? 12 #-6 2.11 158616 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 g5 5.h4xg5 e2f3 6.g6 f1g2 >>? <12> #-6 2.12 159367 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 g5 5.h4xg5 e2f3 6.g6 f1g2 >> >> >>analysis with forward pruning: >>------------------------------ >> >> depth value time nodes pv >> 1 -5.23 0.00 2 1.g3h3 >> <1> -5.23 0.00 3 1.g3h3 >> 2 -5.35 0.00 38 1.g3h3 f2 2.h3g2 >> <2> -5.35 0.00 48 1.g3h3 f2 2.h3g2 >> 3 -5.37 0.00 84 1.g3h3 f2 2.h3g2 e3e2 >> <3> -5.37 0.00 90 1.g3h3 f2 2.h3g2 e3e2 >>? 4 -510.92 0.01 194 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >>? <4> -510.92 0.01 207 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 5 -510.92 0.02 322 1.g3h3 f2 2.h3g2 >> <5> -510.92 0.02 335 1.g3h3 f2 2.h3g2 >> 6 -510.92 0.03 531 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> <6> -510.92 0.03 552 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 7 -510.92 0.03 1182 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 f2f1Q >> 4.h2g3 >> <7> -510.92 0.03 1203 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 f2f1Q >> 4.h2g3 >> 8 -510.98 0.04 2726 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 e2f3 >> 4.h2h3 f2f1Q 5.h3h2 >> <8> -510.98 0.04 2776 1.g3h3 f2 2.h3g2 e3e2 3.g2h2 e2f3 >> 4.h2h3 f2f1Q 5.h3h2 >> 9 -510.97 0.08 5403 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 f1f2 5.h2h3 e2f3 >> <9> -510.97 0.08 5460 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 f1f2 5.h2h3 e2f3 >>? 10 -512.01 0.16 12077 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 >>? <10> -512.01 0.16 12228 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 >> 11 -512.03 0.46 33004 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 6.g3g2 >> <11> -512.03 0.46 33351 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 e2e3 5.h2g3 f1xa6 6.g3g2 >>? 12 #-6 1.71 135713 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 g5 5.h4xg5 e2f3 6.g6 f1g2 >>? <12> #-6 1.72 136462 1.g3h3 f2 2.h3g2 e3e2 3.g2g3 f2f1Q >> 4.g3h2 g5 5.h4xg5 e2f3 6.g6 f1g2 >> >> >>Best wishes, >>Steffen.
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.