Anthony C on Games 8 and 9

[AdminX]

"A black day for the Zappa team. Zappa got a very good position with Black in a Ruy Lopez, got in time trouble, blundered, and lost. After Qd8 Qb8 Qg8, White has the amazing plan of g5-g6, Kh5, and Bxh6, and can win despite being down a full exchange. Black could probably play for a win after e4 instead of Qxb5, or a draw after c3 instead of Qd8.

In the second game, Rybka simply outplayed Zappa, and again got a position where its deep search was able to find some tricks. If you look at the position 5 full moves before Rxc4 it is hard to believe that Black is winning. However in the endgame Rybka traded rooks and despite having an eval of +7 (Zappa only +2 for White) the game was drawn.

I actually think this match showcases the differences between Rybka and Zappa quite well. Zappa's knowledge is in its evaluation and its relatively accurate guesses about positions. Rybka's knowledge is in its intelligent search which lets it see very deeply very quickly. Interestingly most people associate a gradual score rise with a superiority in evaluation, when in fact it usually indicates a superiority in search, as the opponent is making many little blunders. In contrast when one engine has a superiority in evaluation the score will usually rise sharply after a move because suddenly the engine can secure a positional advantage (whatever the term is that the other engine is unaware of).

Two years ago I would have told you that a good evaluation is more important than a good search, but now I am not so sure. At the very least Rybka has proven that even today's engines on big hardware (Zappa) still make many search errors, especially at such quick timecontrols as 60+20."

[Nid Hogge]

Yeah, Rybka get's to scary depths in 40/40 matches..this deep ability gives it the edge I guess..(with good evaluation ofcourse).

[AdminX]

Yeah, Rybka get's to scary depths in 40/40 matches..this deep ability gives it the edge I guess..(with good evaluation ofcourse).

Yeah, I found his (Anthony's) comments on the Hiarcs Forum.

http://www.hiarcs.net/forums/viewtopic. ... 5981fcba78

[Rolf]

"A black day for the Zappa team. Zappa got a very good position with Black in a Ruy Lopez, got in time trouble, blundered, and lost. After Qd8 Qb8 Qg8, White has the amazing plan of g5-g6, Kh5, and Bxh6, and can win despite being down a full exchange. Black could probably play for a win after e4 instead of Qxb5, or a draw after c3 instead of Qd8.

In the second game, Rybka simply outplayed Zappa, and again got a position where its deep search was able to find some tricks. If you look at the position 5 full moves before Rxc4 it is hard to believe that Black is winning. However in the endgame Rybka traded rooks and despite having an eval of +7 (Zappa only +2 for White) the game was drawn.

I actually think this match showcases the differences between Rybka and Zappa quite well. Zappa's knowledge is in its evaluation and its relatively accurate guesses about positions. Rybka's knowledge is in its intelligent search which lets it see very deeply very quickly. Interestingly most people associate a gradual score rise with a superiority in evaluation, when in fact it usually indicates a superiority in search, as the opponent is making many little blunders. In contrast when one engine has a superiority in evaluation the score will usually rise sharply after a move because suddenly the engine can secure a positional advantage (whatever the term is that the other engine is unaware of).

Two years ago I would have told you that a good evaluation is more important than a good search, but now I am not so sure. At the very least Rybka has proven that even today's engines on big hardware (Zappa) still make many search errors, especially at such quick timecontrols as 60+20."

With respect I must disagree. What the author of Zappa doesnt see is that he's caught in a lingual trap. If a program would evaluate the deep positions carefully and exactly enough it had no horizon limitation. I think one cannot argue that Rybka has a "better" search and Zappa the "better" evaluation, no, if the search is well, it's because the evaluation is also well. All that must be taken with the necessary relativation because what is a computer program worth against the human chessplayer, if it can only play faultlessly to a certain depth? Ok, a human player does also a lot of nonsense in much less deeper stages... but this is more a practical problem not a system-immanent boundary/handicap. We have plenty of super GM who calculate faultlessly and who therefore eat a computer program/machine left-handedly. To avoid this will happen, the computer side is eagerly watching for blitz or rapid games.

But I digress. Rybka is much better than Zappa and only lost real or potential points because of Erdo's sensational preparation against Rybka's endgame defects. Duh!