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WAC.163: 662 node search tree
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Pradu Kannan



Joined: 11 Mar 2006
Posts: 287
Location: Atlanta, GA
PostPost subject: Re: WAC.163: 662 node search tree    Posted: Wed May 02, 2007 1:18 am Reply to topic Reply with quote
sje wrote:
Dann Corbit wrote:
I mean, 662 nodes for a depth 11 mate is borderline ridiculous!

Some might say that spending tens to hundreds of milliseconds at a node is just as ridiculous.

From what I know of Paradise, it was never tried on WAC.163, but I'm fairly sure that it could have solved the problem with under 500 nodes and maybe only 250 or less. And I think that a strong human with the assistance of paper and pencil (or the electronic equivalent) could do the same. Remember that nearly all of the problems in WAC and BWTC came from human games in the first place.

Consider the human correspondence chess player. With several days to a week or so for each move, there's plenty of time for leisurely analysis. One way of doing the analysis is to get a big piece of paper and start to draw a search tree with the nodes labeled with active attack and defend issues. The human extends the tree one node at a time with a different algorithm based on which side is on the move. The player adds a node for his/her choice based on which of all the lines seems the most promising. For the opponent's choice, the node added is the one that best refutes the current threat at any level of the threat. In both cases there's a slight bias for shorter threats and faster/early refutations.

Now add a simple computer program that replaces the paper and pencil and keeps track of the tree. Add to the program a set of functions (productions) that measures the relative nastiness and speed of a threat along with a sorting routine that picks the best one. Then add a set of defensive productions that measure at all levels of a threat the relative power of possible refutations and a companion sorting routine. Wrap all of this together and you've got the basics behind Symbolic's mate search.
If I'm understanding correctly, it seems you work on this by a rate-of-change of score approach instead of actual scores and give the lines with higher rate of change for either side greater depth. Quite an interesting extension mechanism but the most interesting part is the implementation of how your program figures out how high the rate-of-change of score is. I believe this can be applied to extension and pruning decisions of traditional alphabeta trees. Rate of change information could be propogated back up to the root and also the use of hashtable entries as nodes may help comparing rate of change across the alpha-beta tree.

Last edited by Pradu Kannan on Wed May 02, 2007 1:22 am; edited 1 time in total
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Display posts from previous:   
Subject Author Date/Time
WAC.163: 662 node search tree Steven Edwards Tue May 01, 2007 4:04 am
      Re: WAC.163: 662 node search tree Pradu Kannan Tue May 01, 2007 5:40 am
            Re: WAC.163: 662 node search tree Steven Edwards Tue May 01, 2007 11:25 am
                  Re: WAC.163: 662 node search tree Pradu Kannan Tue May 01, 2007 3:32 pm
                        Re: WAC.163: 662 node search tree Steven Edwards Tue May 01, 2007 6:37 pm
                              Re: WAC.163: 662 node search tree Tony Wed May 02, 2007 6:27 am
                                    Re: WAC.163: 662 node search tree Steven Edwards Wed May 02, 2007 10:36 am
      Re: WAC.163: 662 node search tree Dann Corbit Tue May 01, 2007 6:19 am
            Re: WAC.163: 662 node search tree Steven Edwards Tue May 01, 2007 11:27 am
                  Re: WAC.163: 662 node search tree Dann Corbit Tue May 01, 2007 10:18 pm
                        Re: WAC.163: 662 node search tree Steven Edwards Tue May 01, 2007 11:59 pm
                              Re: WAC.163: 662 node search tree Slater Wed May 02, 2007 12:46 am
                              Re: WAC.163: 662 node search tree Pradu Kannan Wed May 02, 2007 1:18 am
            Re: WAC.163: 662 node search tree Steve Maughan Tue May 01, 2007 11:33 pm
                  Re: WAC.163: 662 node search tree Steven Edwards Wed May 02, 2007 12:39 am
                        Re: WAC.163: 662 node search tree Steve Maughan Wed May 02, 2007 12:44 am
                              Re: WAC.163: 662 node search tree Steven Edwards Wed May 02, 2007 1:19 am
                                    Re: WAC.163: 662 node search tree Steven Edwards Thu May 03, 2007 9:00 pm
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