Author: Robert Hyatt
Date: 19:22:28 07/14/04
Go up one level in this thread
On July 14, 2004 at 17:03:33, Omid David Tabibi wrote: >On July 14, 2004 at 17:00:04, Matthew Hull wrote: > >>On July 14, 2004 at 16:53:39, Omid David Tabibi wrote: >> >>>On July 14, 2004 at 16:44:00, Peter Berger wrote: >>> >>>>On July 14, 2004 at 12:56:10, Omid David Tabibi wrote: >>>> >>>>>On July 14, 2004 at 12:34:18, Peter Berger wrote: >>>>> >>>>>>On July 14, 2004 at 12:28:29, Omid David Tabibi wrote: >>>>>> >>>>>>>On July 14, 2004 at 12:19:24, Peter Berger wrote: >>>>>>> >>>>>>>>On July 14, 2004 at 11:41:04, Omid David Tabibi wrote: >>>>>>>> >>>>>>>>>On July 14, 2004 at 11:38:31, Peter Berger wrote: >>>>>>>>> >>>>>>>>>>On July 14, 2004 at 11:26:47, Omid David Tabibi wrote: >>>>>>>>>> >>>>>>>>>>>On July 14, 2004 at 11:12:14, Fernando Villegas wrote: >>>>>>>>>>> >>>>>>>>>>>>Not at all, Omid >>>>>>>>>>>>If you already have a parallel engine you should run it into a >>hardware capable >>>>>>>>>>of getting all its power. >>>>>>>>>>> >>>>>>>>>>>I understand that you are going to provide the hardware, right? >>>>>>>>>>> >>>>>>>>>>>It is not something personal; next year I will have the needed >>hardware, but >>>>>>>>>what about others? Deep Sjeng and ParSOS were also >>parallel engines, but ran on >>>>>>>>>single processor not because they thought >>it was better, but because they did >>>>>>>>>not have access to a fast >>multiprocessor machine. >>>>>>>>> >>>>>>>>>> >>>>>>>>>>I wonder what except the results changed from two weeks ago to now to >>make you >>>>>>>>imply this is an unfair event and go on raving about it ?! >>>>>>>>>> >>>>>>>>>>Weren't you even one of the organizers? >>>>>>>>> >>>>>>>>>Yes, and I complained loudly about it even before the event. >>>>>>>> >>>>>>>>Actually I still think this is argueing with hindsight. Diep and Crafty >>finished >>>>>>3rd and 4th, a result that surprised some of the present >>programmers. >>>>>> >>>>>>>>It seemed to concern no one last year when it was only the professionals >>who >>>>>>came with superior hardware. >>>>>>>> >>>>>>>>To quote another programmer from memory: "I typically get 80% in tests >>against >>>>>>Crafty, so on a Quad it might get 30% or sth like that ". >>>>>>>> >>>>>>>>And we don't know how the results would have looked like in a single CPU >>event >>>>>>either - before the tournament it was "Crafty is a miserable >>program that I can >>>>>>beat on any hardware" (simplified and no quote) - >>>>>>> >>>>>>>This quote is not from me. >>>>>> >>>>>>And I didn't imply any different. >>>>>> >>>>>>> >>>>>>> >>>>>>>>at least one part of this >>>>>>>>statement turned out to be untrue. >>>>>>>> >>>>>>>>Maybe the hardware impact is a little overrated in this discussion >>anyway. Jonny >>>>>>on a PIV2.8 e.g. nearly finished Junior on a Quad. >>>>>>> >>>>>>>You want to measure the hardware impact, just do the following: >>>>>>> >>>>>>>Run the Crafty benchmark at a fast single processor machine, and also on >>the >>>>>quad machine: >>>>>>> >>>>>>>ratio = (benchmark on quad) / (benchmark on single proc) >>>>>>> >>>>>>>(the ratio would be about 4) >>>>>>> >>>>>>>Next, for each move of Crafty in the tournament, divide the thinking time >>by the >>>>>'ratio' above, to get a new time: >>>>>>> >>>>>>>time2 = (original time spent on the move) / ratio >>>>>>> >>>>>>>Now just count how many times Crafty changed its PV after 'time2'... (In >>other >>>>>words, how many times Crafty changed its PV after thinking for 1/4 >>of the time >>>>>on the move.) >>>>>> >>>>>>This test sounds more scientific and logical than it is. You also would >>have to >>>>identify the moves that would make any difference to the result of >>the game. >>>> >>>>>>I can easily reproduce all critical moves of the Falcon-Crafty game on my >>>>>>notebook for black. I already asked you in another message if more time >>would >>>>have made any difference for Falcon for two of its critical mistakes >>- you >>>>didn't answer yet. >>>>> >>>>>Just count the number of times Crafty changed the PV after 1/4 of its >>thinking >>>time (including pondering), and see how many of them were critical, >>and >>>prevented a loss. >>>>> >>>>>You will find many of them. Here is one I remember clearly: After Falcon's >>>>>...Ra5 in the endgame, Crafty wanted to repeat the position at first (score: >>>>>0.00). It thought for a long time, and then changed the PV to other move, >>which >>>was winning. But you will find many other moves in the earlier stage >>of the >>>game, which would have resulted in a loss were they played (after >>thinking for >>>1/4 of the time). >>>> >>>>I think you maybe misunderstood me here because of the heat of the >>discussion. >>That I can easily reproduce Crafty's moves on my notebook doesn't >>mean that all >>its moves were found fast and easily :). >>>> >>>>From memory there were two moves in the tournament where Crafty changed its >>mind >>very late and that turned out to be of big importance. >>>> >>>>Kb6 (or whatever the move after Falcon's Ra5, no surprise that we both >>remember >>this one) >>> >>>OK, so at least you agree that without the 4x hardware advantage Crafty >>wouldn't >have got more than a draw. >>> >>> >>>> and g5 in the game against Diep. >>>> >>>>In case there were other moves like that, I am at least not aware of it. >>>> >>>>I expect Bob to offer Crafty's logfiles for download soon as he did for >>cct-6, >>so maybe we should delay this discussion until we can just discuss the >>real data >>( I don't have access to the Opteron anymore). >>>> >>>>I would still be interested to know about the critical points from Falcon's >>>>side; Ra5 is a trial to avoid repetition - you have to search very deep to >>>>dismiss it. >>> >>>One iteration deeper Falcon switches to the other move which results in actual >>>threefold repetition. >>> >>>In other words, had Crafty not had the hardware advantage it would have missed >>>the win, and had Falcon had the 4x hardware it would have found the correct >>draw >(and with that hardware advantage probably also found a correct winning >>line). >Right? >> >> >> >>Why don't you just test it. Download crafty19.15 and setup the appropriate >>time controls for each side and start from some move in the actual game. >> >> >>Then we won't be in fantasy land anymore, but in the land of fact. > >It is not fantasy. During the actual game Crafty found the correct move in the >endgame after a very long search (previous best move was threefold repetition). >Peter was the operator, and has said the same in the post above. Quoting him: > >"From memory there were two moves in the tournament where Crafty changed its >mind very late and that turned out to be of big importance. Kb6 (or whatever the >move after Falcon's Ra5, no surprise that we both remember this one)" Yes, but you are making _assumptions_ based on facts not in evidence. For example, Crafty can take a long time whenever it wants. Slow the hardware down by a factor of 3, to equalize it to your amd64, it it _still_ might find the move, because it just might do a deep search. It has a rule about using lots of time to search "interesting" ply-1 root moves deep into a search. So it is hard to say whether it would have missed that move, or it would have taken a lot longer to still find it... > > >> >> >>:) >> >> >> >>> >>> >>> >>>>And Ra8 is probably not about search at all. >>>> >>>>Peter
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