Author: Uri Blass
Date: 13:32:53 02/15/04
Go up one level in this thread
On February 15, 2004 at 14:13:05, Christophe Theron wrote: >On February 15, 2004 at 12:32:55, Tord Romstad wrote: > >>On February 14, 2004 at 13:16:15, Christophe Theron wrote: >> >>>What I have always tried to do is to hide the details of what's inside Chess >>>Tiger (in order to protect my work a little bit) but still explain what my >>>methodology (or work philosophy) was (in order to somehow give back to the >>>community). >>> >>>I think it's important to have strong guidelines in your work. Some of them come >>>from your knowledge of information processing in general (be careful not to >>>create bugs, don't waste resources, never trust Microsoft...), and some of them >>>are specific to the domain of chess programming and took me years to figure out. >>>For example: >>>* don't compute something in advance if you are not sure you will use it, >>>because chances are that you will get a cutoff before you need it (remember it's >>>just a guideline - sometimes you can break this rule). >>>* you need a very accurate way of measuring progress, or you will not make >>>progress at all. >> >>Yes. Measuring progress is the biggest problem of all, once your engine has >>reached a certain level. I am very frustrated and confused about the strength >>of my latest development versions right now. I have three different versions, >>and version A beats version B, version B beats version C, and version C beats >>version A. In all cases, the winning margins are clearly statistically >>significant. >>I have no idea which version is the strongest, of course. >> >>>* Any change can make your program significantly weaker. You need to test your >>>changes (with the method you have built) very often. >>>* People believe that chess is about evaluation, but actually it's all about >>>search (I'm trying very hard to break this rule, because it must be wrong from a >>>mathematical point of view, but it's really difficult). >> >>Here I agree with Martin. The evaluation function is my main tool for shaping >>the tree, and improving the eval usually also improves the speed and >>accuracy of the search. > > > >I don't use the evaluation to shape the tree in Chess Tiger. If I change the >evaluation, the tree remains similar. Of course it will not be exactly the same, >so naturally the evaluation has an indirect impact on the shape of the tree, but >I mean that the evaluation is not what I use to decide to prune a branch or to >extend one. By using null move you use evaluation to decide if to prune lines. I believe that not using evaluation by more ways as one of the factors to decide if to prune a branch or to extend a branch is a mistake. Uri
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