Author: Robert Hyatt
Date: 06:52:49 02/28/06
Go up one level in this thread
On February 28, 2006 at 08:46:32, Vasik Rajlich wrote:
>On February 27, 2006 at 11:51:09, Miguel A. Ballicora wrote:
>
>>On February 27, 2006 at 09:41:37, Tord Romstad wrote:
>>
>>>On February 27, 2006 at 06:48:18, Tord Romstad wrote:
>>>
>>>>I'll try to write an explanation on my web page, and refer to that one
>>>>in the future. I hope to have it ready today or tomorrow. Stay tuned!
>>>
>>>My first draft is ready:
>>>
>>>http://www.glaurungchess.com/lmr.html
>>>
>>>Comments, corrections and suggested additions or improvements
>>>are welcome.
>>
>>I was away from CC 3 years and I was wondering what this technique was. Thanks
>>for the explanation, it was pretty clear.
>>Unfortunately, I tried this ~5 years ago in several ways and it did not work .
>>It was not my idea, it was Bob Hyatt's here at CCC. I still have in my code this
>>ancient lines (nodecount is moves searched):
>>
>> #if 0
>> /* BH's suggestion, modified */
>> if (nodecount == 15 && depth == 1) {
>> break;
>> }
>> #endif
>>
>> #if 0
>> /* BH's suggestion */
>> if (nodecount == 15 && depth == 2) {
>> depth--;
>> }
>> #endif
>>
>> #if 0
>> /* BH's suggestion, modified */
>> if (nodecount == 15 && prun_cand ) {
>> break;
>> }
>> #endif
>>
>
>Note that the method Tord describes is quite a bit different. Most important is
>that the late moves are reduced rather than thrown away - I see now why Tord
>insisted on that term :)
>
>Vas
I don't think he is "throwing away moves" although without all the code, it is
hard to tell. But the "depth--" appears to be the usual "reduction" idea...
which is what we were trying way back when. (Bruce Moreland and myself,
possibly others). We just never did much "qualification" on what to reduce and
what to not reduce, particularly the history counter idea, which is the
important idea in today's approaches...
>
>>Considering that after moves 15 the order in my case is determined by history
>>heuristics, one the options literally was history pruning, and I tried
>>reductions too. The tree decreased but my engine (gaviota) played terrible.
>>Maybe I should give it a try again. As you can see, the implementation was too
>>raw.
>>
>>Miguel
>>
>>>
>>>The only two engines I mention in my "Sample Code" paragraph are
>>>Fruit and Glaurung. This is because of ignorance, and not because
>>>of disrespect to other authors. If you are the author of an open source
>>>engine using history pruning (or whatever you prefer to call it) and
>>>wants it to be mentioned on my page, please let me know.
>>>
>>>Tord
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