Author: Robert Hyatt
Date: 12:29:02 11/13/00
Go up one level in this thread
On November 13, 2000 at 14:05:23, Uri Blass wrote: >On November 13, 2000 at 13:13:33, Jeremiah Penery wrote: > >>On November 13, 2000 at 10:18:30, Robert Hyatt wrote: >> >>>On November 13, 2000 at 02:46:37, Jeremiah Penery wrote: >>> >>>>On November 12, 2000 at 02:42:20, Uri Blass wrote: >>>> >>>>>On November 12, 2000 at 01:41:43, Helmut Conrady wrote: >>>>> >>>>>>[D]8/8/8/2KR4/3R4/2k1b3/8/8 w - - >>>>>> >>>>>>In a test with Fritz 6a, Junior 6, Shredder 4, Century 1.2 Tiger 12, Hiarcs >>>>>>7.32, Nimzo 7.32 no one did. >>>>> >>>>> >>>>>It is an easy position. >>>>> >>>>>You only need the 5 piece tablebases. >>>>> >>>>>Uri >>>>>> >>>>>>What about an algorithm like this: if i have a graet material advantage and can >>>>>>not make any progress after some moves I will check wheter it can be a draw! >>>>>> >>>>>>Helmut >>>>> >>>>>You should explain how to check it and the problem is that you may expect the >>>>>opponent to get a position when you have small material advantage. >>>>> >>>>>The alpha beta does not tell you about second best move so you will not know >>>>>that you cannot make progress before it is too late. >>>> >>>>I think you can check to see if the score is the same for some number of >>>>iterations, and if there have been no captures (or certain other moves) in that >>>>time, then you can return a draw score. I think I remember someone talking >>>>about implementing something like this (Hossa, IIRC) some time back. >>>>I'm trying to implement something similar to this in Crafty right now, but I'm >>>>having difficulty finding exactly where the code needs to go. >>> >>> >>>This is a very old idea. Dave Slate implemented what he called the "weariness" >>>factor in chess 4.x... the idea was that as the 50 move rule draws closer, the >>>score approaches a draw. I used to do this in Crafty in fact, but it has some >>>problems when dealing with the hash table since the 50 move counter isn't part >>>of the stuff used to make the signature. >>> >>>But the idea is reasonable, and we copied it in Cray Blitz. The only issue is >>>_when_ do you let it kick in? 20 moves after you reset the 50 move counter? >>>30? 15? >> >>My idea was not to use the 50-move counter, but something else. If the output >>looks like this: >> >> 8-> 0.13 4.50 1. Rd8 Bxd4+ 2. Rxd4 Kb2 3. Rd8 Ka1 >> 4. Kc6 Ka2 5. Rh8 >> 9 0.24 4.50 1. Rd8 Bxd4+ 2. Rxd4 Kb2 3. Rd8 Ka1 >> 4. Kc6 Ka2 5. Rh8 Ka1 >> 9-> 0.34 4.50 1. Rd8 Bxd4+ 2. Rxd4 Kb2 3. Rd8 Ka1 >> 4. Kc6 Ka2 5. Rh8 Ka1 >> 10 0.56 4.50 1. Rd8 Bxd4+ 2. Rxd4 Kb2 3. Rd8 Ka1 >> 4. Kc6 Ka2 5. Rh8 Ka1 6. Rg8 >> 10-> 0.76 4.50 1. Rd8 Bxd4+ 2. Rxd4 Kb2 3. Rd8 Ka1 >> 4. Kc6 Ka2 5. Rh8 Ka1 6. Rg8 >> >>Then to score it as a draw after 3 iterations where the same score is output. > >It is a bad idea because it is possible that 1.Rd8 Bxd4+ 2.Kd3 is winning so by >scoring Rd8 as a draw you are going to miss 1.Rd8 that is winning and play 1.Rd7 >that gives only 1.1 pawns advantage that is not enough to win. > >Uri Also I don't believe that 3 successive iterations with the same score means that no progress can be made. Maybe three successive _moves_ in the game with no score change indicates something. But not three successive iterations. I see this all the time.
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