Author: Dave Gomboc
Date: 23:09:45 09/12/01
Go up one level in this thread
On September 11, 2001 at 17:43:44, Robert Hyatt wrote: >On September 11, 2001 at 17:12:16, Bruce Moreland wrote: > >>On September 11, 2001 at 15:04:28, Robert Hyatt wrote: >> >>>On September 11, 2001 at 12:54:32, Bruce Moreland wrote: >>> >>>>On September 11, 2001 at 11:40:22, Rafael Andrist wrote: >>>> >>>>>On September 11, 2001 at 10:36:00, Robert Hyatt wrote: >>>>> >>>>>>On September 10, 2001 at 13:37:58, Rafael Andrist wrote: >>>>>> >>>>>>>On September 07, 2001 at 13:41:57, Robert Hyatt wrote: >>>>>>> >>>>>>>>I did this in Cray Blitz _many_ years ago (coordinated squares is the term I >>>>>>>>hear used most often). And I was amazed that it took longer to find the right >>>>>>>>move. After a mountain of debugging output, I discovered what I mentioned >>>>>>>>previously... "hash grafting" (the art of grafting parts of the tree from >>>>>>>>one zone to another by using the hash table) was helping the dumber version, >>>>>>>>but not the smarter one. >>>>>>>> >>>>>>> >>>>>>>You mix some things together! Knowledge about opposition is only one of the >>>>>>>tools you need to to construct a system of co-ordinated squares (german: >>>>>>>Gegenfeldsystem). If you implement this correctly, you should find the correct >>>>>>>move instantly i.e at ply 1 as my chess program Wilhelm does. >>>>>>> >>>>>>>Rafael B. Andrist >>>>>> >>>>>> >>>>>>You find the right move instantly... But you don't _know_ it is the right move >>>>>>until the score jumps. It _could_ just be a draw. And in the case of Cray >>>>>>Blitz, using coordinated squares, it took 25-26 plies to see the big score. >>>>>>It saw the right move normally at around ply=18 with the +2.5 score. With >>>>>>the coordinated squares stuff, it got the Kb1 move instantly, but the score >>>>>>didn't reach +2.5 until 7-8 plies longer than the simple version. >>>>>> >>>>>>That was the point. The better the move ordering, the less "grafting" helps >>>>>>a shallow search find a deep solution. >>>>> >>>>>I now by eval from ply 1 that i win a pawn. In Fine 70, White is already a pawn >>>>>up, so I get instantly an evaluation around 2. >>>>> >>>>>Rafael B. Andrist >>>> >>>>Nobody has written an article on how to use coordinate squares in a chess >>>>program. If you write this up, I bet the ICCAJ would publish it. >>>> >>>>bruce >>> >>> >>>What I did was pretty simple... and was very similar to what I do in pawn-only >>>endings in Crafty. IE detecting/maintaining opposition. Note that I didn't >>>keep this code in Cray Blitz. It was just something that Harry or someone >>>suggested that I try to see what I thought. I ran into problems in that in >>>some cases, staying on the right "square" is the grossly wrong plan, when you >>>do that rather than centralizing. >> >>I don't think that coordinate squares have anything to do with maintaining >>opposition. >> >>bruce > >Of course it doesn't. I do opposition in crafty. The coordinate squares idea >came from Ivan Bratko (from the Bratko/Kopec test from the early 80's) in a >conversation we had in 1984 in London at the Levy vs Cray Blitz match. Didn't >mean to 'connect' the ideas at all, other than if you look at many of the >endgame books, they explain coordinate squares in pretty simple terms, that is >pretty easy to compute just like normal/distant opposition. But it doesn't >(in the cases I have studied) guarantee the win of material, which is what I >didn't understand in the post I queried. > >I should say that coordinate squares is related to opposition, as it does >translate to opposition in many cases, after a lot of moves. The opposition is a special case of coordinate squares. The theory of coordinate squares have existed since long before 1984. Dave
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