Author: Tord Romstad
Date: 02:16:23 04/15/04
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On April 14, 2004 at 19:54:38, rasjid chan wrote: >I am now using the the simplest mdtf, nothing except adding about >10-20 lines at the root-search and it seems to work equally well as >my aspiration/pvs. Your aspiration/PVS was probably still rather clean and simple. For a complex, highly developed and very efficient PVS search, changing to MTD would be a big and difficult rewrite. There is a considerable amount of tricks and techniques which work well with one algorithm and not with the other. If you take a big and complicated PVS engine like Crafty and change it to use MTD, I think you would need several months to make it anywhere near as efficient as the current PVS search. >I have fail-soft, hash TT with 1 bound, only step +/-1. That's one of the reasons why you only had to add 10-20 lines of code, of course. :-) >I don't need to change anything(yet)in other parts of my program. The >same hashing remains. But as Vasik mentioned before, it is crucial to >mdtf that fail-soft is w/o bugs and CORRECT. I think routinely >failing/hashing outside bounds itself may not be sufficient. This depends on your definition of sufficient, of course. I still use a quick and dirty fail-soft which I wrote in a few minutes without even thinking. I am sure it is nowhere near perfect, and this discussion has convinced me that I should take a look at it and see if I can find any improvements, but I find it hard to believe that I would get a big leap in playing strength by doing this. My quick and dirty fail-soft seems to be doing OK. >I have not yet examine if other things need to be changed to make mdtf >efficient.I guess most who try mdtf will abandone it as it usually will be >clearly slower. If you already have a well-oiled and highly optimized PVS, this is probably correct. But if you haven't yet reached that stage, I would claim precisely the opposite. It is much easier to write an efficient MTD(f) than an efficient PVS. Tord
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