Information from Chessbase website:
Deep Rybka 4 – Multiprocessor Version
Rybka 4, the world’s strongest chess program, leads all ranking lists clearly, with ratings well above Elo 3000. Now Rybka 4 is here, with a dramatic improvement of at least 80 Elo points.
Rybka 4, which translates to "little fish", is the shooting star of computer chess and the reigning world champion, having won its title in Amsterdam 2007.
But strength is not everything. Today the main use of chess software is interactive analysis. Rybka's superior playing strength helps you to quickly assess a position. But analysis with Rybka 4 is much more than just evaluations and best moves. In the user interface designed by ChessBase, Rybka 4 introduces several ground-breaking new analysis features:
Monte Carlo Analysis yields precise evaluations by playing thousands of ultra-fast games in a few minutes in a given position. This is very much like using game result statistics, something human players do when choosing their opening variations. Monte Carlo Analysis can be used in any position, but generally it's most useful in two types of positions:
Endgames – engines often give high scores to drawn endgames (and sometimes low scores to winning ones). Monte Carlo recognises fortresses and other no-progress situations. It's also good in rook endgames, which are another computer problem.
Positions where one side has made a big material sacrifice for slow compensation (i.e. not just tactics). For instance you can find lots of piece sacrifices in famous grandmaster chess games which no computer will correctly appreciate and which Monte Carlo gets right.
Sampled Search gives detailed information about the search process, showing scores and alternative moves in the main line. This is helpful when the program searches for a long time in one position. It lets the users see how the engine is thinking and making its decisions.
Note that in in the live search you can see that the Rybka engine is working on Kasparov's famous 30.Rxb7 sacrifice, which has not turned up in the engine window yet (it will become the main variation after the next iteration). Note too that the square Chess Informant symbol behind certain moves means that these are forced.
Singular Moves are annotated graphically. This indicates situations where only one clearly best move exists.
Look for win: whenever you feel that there should be a forced win in a position you can explicitly ask for it. Rybka then searches for a decisive move, considerably faster than in normal analysis.
Persistent Hash: Rybka can save its hash tables between analysis sessions to preserve valuable information already accumulated in the search tree.
The author of Rybka, Czech-American International Master Vasik Rajlich, has implemented an extraordinary understanding of dynamic factors into his program. This often results in long-term pawn or exchange sacrifices and an active positional playing style resembling human chess. Rybka scores well in all types of situations but dominates especially in asymmetric positions which arise e.g. from Sicilian systems.
The success of the program stems from dedicated team work: IM Iweta Rajlich, rated 2417, is the main tester; Jeroen Noomen contributes opening theory and tournament preparation; IM Larry Kaufman develops positional algorithms.
System requirements: Minimum: Pentium 1 GHz, 512 MB RAM, Windows Vista or XP (SP 2), DVD ROM drive, Windows Media Player 9. Recommended: pc Intel Core Duo 2.4 GHz or higher, 4GB RAM, Windows Vista, GeForce8 or compatible graphics card with 256 MB RAM or higher, 100% DirectX compatible sound card, Windows Media Player 11, DVD ROM drive.
Technical Support on chess software is very limited. Please contact chessbase directly with any installation or technical help.
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