Author: Ulrich Tuerke
Date: 03:17:40 03/08/01
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On March 08, 2001 at 05:08:03, Matt McKnight wrote: >oops, messed up that last post... > > I've been toying with some move ordering ideas, and I would like to hear some >feedback on them. > > First idea: > Inspired by the killers list, I tried keeping a list of two moves per ply >that seemed to be bad ideas, (score < alpha) and using that to sort those moves >in the future to the end of the list. This seems to give me a small gain. Is >this idea good, or will it cost me in some positions? > > Second idea: > Along with the history heuristic, how about sorting moves by the >positional gain they make? For instance: > score += piece_eval[to] - piece_eval[from]; > >this also seems to help a little. Again, is it helping or not? > >Also, are these ideas dumb and old? At least, your 2nd idea is not new. It has been tried in an old gnuchess version. I don't know if it's still used by the more recent versions of gnu. IMHO, the drawback is that you have to evaluate in addition to the leaves also the inner nodes in order to get these piece values. I experimented a bit with this, but I didn't make a thorough analysis. Since I seemed to observe that the gain from improved move order (which is there IMO) is not really worth the performance loss by evaluating all nodes, I decided not to use this. However I guess that your suggestion may deserve more attention. Uli > >Matt
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