Author: Omid David Tabibi
Date: 06:29:33 10/13/03
Go up one level in this thread
On October 13, 2003 at 09:21:15, Vincent Diepeveen wrote: >On October 13, 2003 at 09:00:43, Omid David Tabibi wrote: > >>On October 13, 2003 at 08:44:36, Vincent Diepeveen wrote: >> >>>On October 12, 2003 at 12:16:42, Omid David Tabibi wrote: >>> >>>if you search 14 ply >> >>You count plies one way, Junior count's them another way, and Falcon counts them >>in its own way. >> >> >> >>>with just 8 plies of mainline at a P3-733 then >>>everyone can understand you forward prune, assuming a normal evaluation. >>> >>>the positions used for your ICGA article were all mating positions, >> >>LOL! You again show that you never read that ICGA article! >> >>In that article I used exactly the positions I mentioned here: >> >>138 Neishtadt positions, 879 ECM positions, 1001 WCS positions, and 434 "mate in >>4" and 353 "mate in 5" positions. > >So kind of a 1000 mating positions. 787 mating positions + 2018 non-mating positions. > >that proofs my point convincingly. Sure, the fact that 28% of the positions were mating positions convincingly proves your point that they were all mating positions... (28% = 100%) > >>:) >> >> >>>now you suddenly use other positions????????? >> >>No, they are the very same positions. >> >> >>> >>>if so why? >>> >>>>On October 12, 2003 at 11:57:02, Vincent Diepeveen wrote: >>>> >>>>>On October 12, 2003 at 10:23:35, Omid David Tabibi wrote: >>>>> >>>>>>On October 12, 2003 at 09:27:09, Tord Romstad wrote: >>>>>> >>>>>>>On October 12, 2003 at 06:32:25, Omid David Tabibi wrote: >>>>>>> >>>>>>>>Recently I conducted some extensive experiments with two versions of Falcon, one >>>>>>>>with checks in quiescence and one without. Falcon already has lots of >>>>>>>>extensions, but adding checks in quiescence resulted in a significant boost for >>>>>>>>tactical strength. >>>>>>>> >>>>>>>>I tested the following options: >>>>>>>> >>>>>>>>a) checks everywhere in quiescence >>>>>>>>b) checks only in the first ply of quiescence >>>>>>>>c) no checks in quiescence >>>>>>>> >>>>>>>>Option 'a' was ruled out after some testing, as it resulted in a total explosion >>>>>>>>of quiescence search. I tried controlling it in some ways, but still the >>>>>>>>overhead was considerably more than the benefit. It seems that The King and >>>>>>>>HIARCS are the only engines using this method. >>>>>>> >>>>>>>These are not the only ones. I am fairly sure Diep searches checks everywhere >>>>>>>in the >>>>>>>qsearch, and Gothmog (my engine) also does. >>>>>> >>>>>>True, I referred to commercial engines. HIARCS and King definitely do checks >>>>>>everywhere in quiescence (with certain limitations of course), but I'm not >>>>>>completely sure about Fritz, Shredder, and Tiger (Junior seems not to have a >>>>>>quiescence at all, but it has a large set of extensions). >>>>>> >>>>>> >>>>>>> >>>>>>>>Option 'b' produces almost the same tactical strength as option 'a', with a >>>>>>>>considerably lower overhead. >>>>>>> >>>>>>>Interesting. I have only tried options 'a' and 'c' myself, and always found >>>>>>>option >>>>>>>'a' to be significantly better (in games as well as test suites). I should >>>>>>>probably >>>>>>>do some experiments with option 'b' as well. >>>>>>> >>>>>>>>Only using checks in the first ply of quiescence, Falcon managed to solve almost >>>>>>>>all tactical positions of LCTII in less than 1 second, >>>>>>> >>>>>>>Very impressive. Gothmog (on an Athlon XP 2.4 GHz) solves the first 8 positions >>>>>>>in >>>>>>>less than a second, but needs 1:18 for number 9, >>>>>> >>>>>>[D]6k1/5p2/3P2p1/7n/3QPP2/7q/r2N3P/6RK b - - 0 1 >>>>>> >>>>>>If you do checks everywhere in quiescence, you should see this immediately. >>>>>>After 1...Rxd2 2.Qxd2 all the rest of the moves are checks until you detect draw >>>>>>by threefold repetition (maybe you've turned off repetition detection in >>>>>>quiescence? or your max extensions limit is too shallow...). HIARCS finds the >>>>>>move at the first iteration! >>>>>> >>>>>>The following is Falcon's analysis (with checks enabled only at the first ply of >>>>>>quiescence): >>>>>> >>>>>>Falcon 0.0.3.5 running on GenuineIntel 733MHz 256MB: >>>>>>depth time nodes nps score variation >>>>>> 6/10 0.16 16k 103k 3.22 1...h5f4 >>>>>> 6/12 0.29 30k 104k 8.55 1...f7f5 1.d6d7 a2a8 2.d4d5 >>>>>> 6/12 0.31 32k 106k 3.47 1...h5f4 1.d6d7 f4e6 2.d7d8q e6d >>>>>> 3.d4d8 g8h7 >>>>>> 8/14 0.43 47k 109k 3.61 1...h5f4 1.d6d7 f4e6 2.d7d8q e6d >>>>>> 3.d4d8 g8h7 4.d8d4 >>>>>> 8/17 0.89 99k 111k 3.50 1...a2d2 1.d4d2 h3f3 2.d2g2 f3f4 >>>>>> 3.d6d7 f4d6 >>>>>>10/19 0.97 108k 111k 3.17 1...a2d2 >>>>>>10/19 11.42 1275k 111k 0.00 1...a2d2 1.d4d2 h3f3 2.g1g2 f3f1 >>>>>> 3.g2g1 f1f3 >>>>>>12/21 11.54 1292k 112k 0.00 1...a2d2 1.d4d2 h3f3 2.g1g2 f3f1 >>>>>> 3.g2g1 f1f3 >>>>>>14/23 12.04 1374k 114k 0.00 1...a2d2 1.d4d2 h3f3 2.g1g2 f3f1 >>>>>> 3.g2g1 f1f3 >>>>>>16/25 14.07 1722k 122k 0.00 1...a2d2 1.d4d2 h3f3 2.g1g2 f3f1 >>>>>> 3.g2g1 f1f3 >>>>>> >>>>>> >>>>>> >>>>>>>25 seconds for number 10, 25 >>>>>>>seconds >>>>>>>for number 11, and doesn't solve number 12 at all (at least not within a few >>>>>>>hours). >>>>>> >>>>>>Falcon doesn't manage to solve number 12 either. >>>>>> >>>>>> >>>>>>>Earlier >>>>>>>versions solved number 9 instantly, but the quick solution turned out to be >>>>>>>caused by >>>>>>>a bug: I had accidentally changed my single-reply-to-check extension to a >>>>>>>two-replies-to-check extension. >>>>>>> >>>>>>>>outperforming the normal >>>>>>>>version (no checks in quiescence). But adding checks in quiescence (although >>>>>>>>only at its first ply) significantly slowed down the engine (from average of >>>>>>>>350kNPS to 150kNPS on my PIII/733MHz) and resulted in a worse branching factor. >>>>>>> >>>>>>>You must have a very inefficient way of generating checks, I think. >>>>>> >>>>>>That's true. Only recently I added checks in quiescence to the engine, and so >>>>>>still haven't written a gen_checks() functions. However, the kind of attack >>>>>>tables I use result in a very speedy generation of captures, which results in a >>>>>>very optimized captures only quiescence. Adding checking moves will slow down >>>>>>the engine considerably anyway, even if I write a good gen_checks()... >>>>>> >>>>>>One thing I have to mention is that in the normal version I never check for >>>>>>check evasions in quiescence. If the side to move is in check and doesn't have >>>>>>any legal non-losing capture, I just return eval(). That's another reason why >>>>>>the normal quiescence is so fast. >>>>>> >>>>>> >>>>>>>I haven't >>>>>>>spent a >>>>>>>lot of time optimising check generation myself, and in my program the NPS drops >>>>>>>by >>>>>>>only about 15%. It would probably be possible to push it below 5% with some >>>>>>>effort. >>>>>>> >>>>>>>>So, it seems that adding checks in quiescence is great for solving tactical test >>>>>>>>suites, but not so for actual game play. The same goes for some of the >>>>>>>>aggressive extensions I tried; great for tactics, poor in games. >>>>>>>> >>>>>>>>I'd be interested to hear others' thoughts on this issue. >>>>>>> >>>>>>>It seems like checks in the qsearch is one of those things that works well in >>>>>>>some >>>>>>>programs, and not in others. Crafty, for instance, seems to do very well >>>>>>>without >>>>>>>any checks whatsoever, >>>>>> >>>>>>I wouldn't say so from a tactical point of view. Whenever the game turned >>>>>>tactical, Crafty didn't have any chance against Falcon with checks in >>>>>>quiescence. But Crafty did search deeper and played a better positional game. I >>>>>>must also add that Falcon uses a huge number of different extensions (I think >>>>>>only HIARCS has more extensions), and so maybe adding checks in quiescence on >>>>>>top of them all isn't such a good idea... >>>>>> >>>>>> >>>>>>>but for me the results without checks are clearly worse. >>>>>>> >>>>>>>Other ideas that I have never been able to make work are recapture extensions >>>>>>>and >>>>>>>all sorts of nullmove pruning except plain R=3 (R=2, R=2.5, adaptive pruning and >>>>>>>verified >>>>>>>nullmove pruning are all clearly worse for me). >>>>>> >>>>>>In Falcon I conducted all the experiments I conducted on Genesis for the paper >>>>>>verified null-move pruning, and got the same results. Plain R=3 was too risky >>>>>>neglecting many tactical shots. I now use a modified version of verified >>>>>>null-move pruning. >>>>> >>>>>This simply is a matter of bad experimentation from your side. >>>>> >>>>>When you do check first ply in qsearch and no dubious forward pruning last ply >>>>>(your search depths are *very* big considering hardware) then at your 'testset' >>>>>that version will outperform any other version trivially with R=3, because it's >>>>>nearly all mating problems. >>>> >>>>You have said this again and again but that doesn't make it true. In my >>>>"testset" there are 138 Neishtadt positions, 879 ECM positions, 1001 WCS >>>>positions, and only 434 "mate in 4" and 353 "mate in 5" positions. Is this what >>>>you call "nearly all mating problems"? >>>> >>>> >>>>> >>>>>>But maybe plain R=3 didn't work for me because I didn't have checks in >>>>>>quiescence, and so it resulted in a very inaccurate search. The only program >>>>>>I've heard which uses plain R=3 is DIEP, which does conduct checks everywhere in >>>>>>quiescence. >>>>> >>>>>You should test R=3/2 too when you forward prune that much. >>>> >>>>How do you know that I forward prune "that much"? >>>> >>>> >>>>> >>>>>> >>>>>>> >>>>>>>>I also considered using some form of static mate threat detection, independent >>>>>>>>of null-move search, but haven't found any interesting way to do so yet. >>>>>>> >>>>>>>I have also experimented with static mate threat detection in the evaluation >>>>>>>function, >>>>>>>but it is very tricky to get it right. Also, all minor bugs are likely to have >>>>>>>catastrophic >>>>>>>consequences (at least if you allow the evaluation function to return a mate >>>>>>>score when >>>>>>>the static mate finder reports a mate in n for the side to move). >>>>>>> >>>>>>>Tord
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