Author: Vincent Lejeune
Date: 03:53:17 10/24/00
Go up one level in this thread
On October 24, 2000 at 02:10:57, Christophe Theron wrote: >On October 23, 2000 at 22:48:12, Robert Hyatt wrote: > >>On October 23, 2000 at 20:50:35, Ratko V Tomic wrote: >> >>>>>> GT has larger-than-life king safety scores. That >>>>>> is all. No different search paradigm or anything else. >>>>... >>>> Christophe specifically said that the search is the same for both >>>> programs. I took that as being true,as it seemed to match my >>>> impression after watching games. It speculates more. But it >>>> isn't searching _differently_ at all. >>> >>> >>>There is quite a bit of space in between, to paraphrase your earlier comment, >>>'large safety score and nothing else' and your current one 'is not searching >>>differently'. The hypothesis I sketched in the previous note is just one of many >>>conceivable ways in between, where one can say 'the search is the same' (i.e. it >>>is using the same iterative alpha-beta & support routines), yet the novelty >>>cannot be said to be merely in a new leaf evaluator (or its weight) but it would >>>be in a way how the inputs and outputs of the search are interacting across >>>iterations via pre/post-processors, as well as how much information is >>>transferred that way (is it just score, hash, history entries & killer moves, as >>>in most programs, or something extra which helps GT make fewer mistakes in >>>deciding to undertake apparently open ended king-side attack). >>> >>>While Christophe did say the search is the same (and one can parse that to mean >>>many things; even Botvinnik's program had alpha-beta search in the lower layer), >>>he also suggested, in response to dismissive comments about the GT style as >>>being just another king safety tweak, that you're welcome to go ahead and >>>increase the king-safety scores in Crafty and see how far that gets it. >> >> >>How do you think I arrived at the _present_ king safety scores? Here is the >>point: >> >>if you have a good search (and CT certainly appears to meet that criterion) >>so that you don't get out-searched very often, then you can be more speculative. >>If you do get out-searched, then you will have massive problems, as CSTal did >>in every group of games I watched it play vs Crafty. >> >>I'd be willing to bet that I can tune my aggressiveness way up, _and_ play that >>version using a big alpha machine (to be sure I don't get out-searched anywhere >>along the way) and the aggressive version would do fine. But as hardware >>becomes more equal, then the 'speculation' had better be right. Else the >>more accurate search will find the holes in the speculation and blow through >>them. > > > > >In many cases we are talking about refutations that can only be found with a >20+ plies search (see 43.Rc6 in the Gambit Tiger - Nimzo 8 game). This is above >the current computers/programs abilities anyway (including mine). There are many many computer move that are refutable with a 20+ search ;))) The stronger attacker players have sometimes some troubles to prove that their sacrifices are correct ... [Event "Wijk"] [Site "?"] [Date "1988.??.??"] [Round "?"] [White "Tal, M."] [Black "Ljubojevic, L."] [Result "0-1"] [ECO "D36"] [WhiteElo "2630"] [BlackElo "2610"] [PlyCount "84"] [EventDate "1988.??.??"] 1. d4 Nf6 2. c4 e6 3. Nc3 d5 4. Bg5 Nbd7 5. cxd5 exd5 6. e3 c6 7. Bd3 Be7 8. Qc2 O-O 9. Nf3 Re8 10. O-O Nf8 11. Rae1 g6 12. Ne5 Ne6 13. f4 Ng7 14. f5 Bxf5 15. Bxf5 Nxf5 16. Rxf5 gxf5 17. Qxf5 Qc8 18. Qf3 Qe6 19. Bh6 Bf8 20. Bxf8 Rxf8 21. e4 Nxe4 22. Nxe4 dxe4 23. Rxe4 f5 24. Rh4 Rf6 25. Qf4 Re8 26. Rh3 Re7 27. Re3 Qd5 28. Rg3+ Kh8 29. Qh4 Ree6 30. Qf4 Qe4 31. Qd2 f4 32. Rd3 c5 33. Nd7 Rg6 34. Nf8 c4 35. Nxg6+ Rxg6 36. Rc3 b5 37. d5 Rg5 38. Rc2 Rxd5 39. Qc3+ Kg8 40. Rc1 Rd3 41. Re1 Rxc3 42. Rxe4 Rc2 0-1 ;))) If it works very often... why change a such beautifull style of play ... PS to all: search your database to see dozens winning sacs by Tal against GM ... > >So it works also when my program is outsearched (which indeed does not happen >often). > > > > Christophe > > > > > >>We actually played tuned like this in several ACM events using Cray Blitz. And >>it worked quite well since we were out-searching all the micros by huge margins. >>But against more equal opponents like deep thought and hitech (and belle in the >>early 80's) this was not a wise thing to try.
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