Author: Uri Blass
Date: 11:05:23 11/13/00
Go up one level in this thread
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
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