Author: Vincent Diepeveen
Date: 17:50:30 12/31/05
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On December 31, 2005 at 20:20:47, Greg Simpson wrote: >Vasik had very logical and persuave ideas. I particularly liked the point that >trading one third speed searching for twenty times the evauation per position >almost has to be good if done right. If that describes what he's doing then it seems however Vasik has taken the other way around, the junior way. The utmost minimum of knowledge in leafs. 3 (Rybka?) or 4 ply depthleft (junior=4?), do set a few pointers which search tables to use, then search with shitzero knowledge last few plies. Very old concept. Called preprocessor. Big disadvantage of it is that those last few plies mess up your positional evaluation and that at 15 0 you play a similar playstrength like 150 0. Your engine goes nullmoving a lot instead of a direct breakthrough. Advantage is you can search at millions of nodes a second. Debugging those tables is relative easy giving a bugfree search, and you're tactical very very strong thanks to a huge nps. If your opponents make big mistakes you'll win every game then of course. Nullmoving in won positions is usually possible. I saw that in the past a lot too. This is how genius killed a lot of engines in the 80s. My amazement would be great however if Rybka keeps killing others in this way. The shock and awe has been delivered at a wrong time in history. That's sad for Vasik. He wins paderborn with it, good for him. He deserves that tournament victory. But you would nearly wish him to win a world title knowing he shows up with a very old concept and gets it to work in a way i'm amazed. It's very nice to know therefore that finally someone else other than junior team is using a by now an alternative approach. Note this concept is especially suited for small slow processors. This concept was used extensively for example by Eric van Rietpaap for those 1 Mhz processors. He used last 3 plies a preprocessor. His explanation for that was: "you need to get some reasonable search depth and a full preprocessor is too weak for that". In his eyes it gave too many positional weaknesses, so his second try for a chessprogram that ran on a pro200Mhz was using a full leaf eval concept. It was running around 200k nps. However if your preprocessor is using some chessknowledge covering important areas and has things very well tuned, then obviously you kick butt with such a concept as no one is prepared to play against engines like that. If Vasik is using this concept in Rybka the main differece between Rybka and junior is that junior is hyper agressive. Whereas some might prefer rybka because it kicks butt, of course from chessplayer viewpoint, junior plays positional more sound as it plays more active thanks to the agressiveness. Yet it has been proven in history that it is very hard to win tournaments and titles with agressive play and there is way more champions that win by passive play. There has been a lot of world champions chess over the past centuries, but i could only write down 3 names that showed real hyperagressive games. Kasparov, Tal and Topalov. I dare to say that from tuning viewpoint, Rybka, Zappa and Fruit really are setting a new standard here. Soon many programmers will follow that. Some 'old' guys and some 'new' guys. Especially the free fruit 2.1 source code will give a big boom there. Just take over its eval, use its extensions, implement it in some other datastructure, add a kingsafety and you have... ... It will happen. What will be more frustrating to Vasik is that he will discover that it is very hard to win rating points with the Eric van Rietpaap concept. It plays great now, but improving it in 2006 now will be a big problem. I've seen how Junior team struggled to get endgame improved and they managed, but it took them 7 years or so, and in middlegame it still makes positional mistakes. That's why most left that concept a long while ago, because the more knowledge you put in the preprocessor, the bigger the positional ratingpoint loss will be in the plies that come after it. So if the concept described is the concept used in Rybka, winning world champs 2006 would mean others won't progress the coming months, which would be wishful thinking with that fruit source code laying for free around. Vincent
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