Author: Peter McKenzie
Date: 13:12:34 09/25/00
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On September 25, 2000 at 13:47:03, Robert Hyatt wrote: >On September 25, 2000 at 11:41:18, David Rasmussen wrote: > >>Am I the only one who >> >>a) thinks that the kind of null move pruning that is done in Hyatt's Crafty is >>the reverse of what Ernst Heinz concludes in his paper about ANMP > > >I hope not. IE here is my code for that: > > null_depth=(depth > 6*INCPLY) ? 4*INCPLY : 3*INCPLY; > >Which says if the remaining depth is more than 6 plies, use R=3, while >if the remaining depth is <= 6 plies, use R=2. > >The "6" is pretty arbitrary. I ran a lot of tests before choosing this >number. Ernst found the same number totally independently of me, although I >think we did use some "common tests" (ie WAC, etc) without knowing what the >other was doing. Since I bought Ernst's book recently (only took 2 weeks to be delivered to New Zealand) I've been thinking about implementing adaptive nullmove pruning. I noticed that Ernst uses a cutover of 8 (instead of 6) in the late endgame (where both sides have 2 or less pieces). Do you do this in crafty? > > > >> >>b) experiences better performance (less nodes, less time etc.) with Hyatt's >>scheme than with Ernst's scheme. >> >>I.E. When I do >> if (depth>6) >> R=2; >> else >> R=3; >>I get the best results. >>Why? > > >What is depth for you? Current ply? Or plies remaining? For me it is >plies remaining before dropping into q-search, which means I am doing the >same thing as Ernst, basically. Your code is the exact opposite of what we >are doing, assuming 'depth' means plies remaining and not depth from root of >the tree.
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