Free Houdini beats commercial Rybka 23.5-16.5

In what could be loosely described as the unofficial world championship of chess engines, free chess engine Houdini beat commercial engine Rybka. The match lasted forty games and the final score was 23.5-16.5. Organizer Martin Thoresen: "I think open source is the way of the future."

For years and years it was Fritz. Then, when top GMs analyzed their games for a chess magazine, sometimes they would mention other engines, like Shredder, Hiarcs or Junior. Then, around 2005, Vasik Rajlich's Rybka started to rule the chess engine scene like Kasparov had done in regular chess. Eventually, in July 2008, Chessbase had to admit that Fritz wasn't the strongest anymore, and started selling Rybka.

With one engine clearly standing out, the chess fan's life was easy. But, as Arne noted in his March 2010 piece, things are much more complicated these days. Several new engines have appeared on the scene, and we hear names such as Firebird and Stockfish. More importantly, many of these engines are open source and so don't cost a dime.

Shortly after Arne wrote his piece, in May 2010, version no. 4 of Rybka appeared on the market. Many experts believed that programmer Rajlich had managed to incorporate the best aspects of other existing engines, and had again created the strongest engine around.

Coincidentally in the same month Robert Houdart's Houdini saw its first release - the first stable release appeared on January 15th, 2011. This engine is not open source (i.e. the programmer's source code is not available), but free to use for non-commercial purposes. The choice of the name, after the famous magician and escapologist, is explained by programmer Houdart on the Houdini website:

The name Houdini was chosen because of the engine's positionaly style, its tenacity in difficult positions and its ability to defend stubbornly and escape with a draw – sometimes by the narrowest of margins. On the other hand Houdini will often use razor-sharp tactics to deny its opponents escape routes when it has the better position.

Houdini has been the subject of controversy as well. For example, it doesn't appear on the rating lists of the Computer Chess Rating List (CCRL) or the Chess Engines Grand Tournament (CEGT) due to possible derivation from the Ippolit series, allegedly plagiarized from Rybka. Houdart admits the influence of other engines on the Houdini website:

Without many ideas from the open source chess engines Ippolit/Robbolito, Stockfish and Crafty, Houdini would not nearly be as strong as it is now.

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Update 20:58 CET Houdini does appear on the CEGT list. Martin Thoresen wrote to us:

Just a note though: CEGT is now testing Houdini. They have it listed on the blitz page. Although they have only tested version 1.5 with 1 core, let's compare it to Rybka with 1 core:

Houdini 1.5 x64 1CPU 3254 (2300 games) Rybka 4.0 x64 1CPU 3180 (4842 games)

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Whatever its origin, one cannot deny that Houdini is a terribly strong chess engine. In his recent Crestbook interview, top GM Peter Svidler agreed:

Russianchessfan: If you had to pick one player to represent earth in a chess game vs. aliens, which active player would it be? You can pick different active players for the white and black side, if you feel it necessary.

Houdini.

And it looks like the latest version of Houdini is even stronger than the latest version of Rybka. In a recent, forty-game match between these two engines, Houdini won with a score of 23.5-16.5. Even more interesting perhaps was that Houdini showed almost frightening human chess, by playing positional pawn sacrifices in many games.



We asked organizer Martin Thoresen, a 29-year-old chess fan from Norway, a few questions:

Why did you organize this match? TCEC is my first own chess project, so I have not organized anything similar in the past. I started the TCEC project simply because I love chess. I am by no means a strong player myself, but I have been following Magnus Carlsen since late 2005 when he played in the World Cup. Later in 2006 I joined the team of one of the largest computer chess engine rating lists and helped them test various engines for a couple of years or so. I gradually lost interest in the pure statistics and decided to create a project where the time control was longer and giving chess fans all over the world a chance to watch it all live on the internet.



The first TCEC event was broadcasted in the summer of 2010. Around that time I experimented a bit with both time control and various engine parameters, but it has since then evolved to what it is now - a more structured project with a fixed set of rules.

The Elite Match is the last event in a TCEC season. First there are regular divisions playing, much like how Tata Steel has divisions, except in TCEC they are played one at a time. The two participants for the Elite Match was selected from the top two finishers of Division I, or the highest division (in season 2 it is called TCEC A).

For all the current rules valid for season 2, I can recommend reading the information page on my website.

How do you do it? Can you describe the set-up? Basically, there's nothing special about the set-up. The hardware used is a standard Intel core 980x, a six-core processor which is over clocked to make it even more powerful.

Then I set up the games in ChessGUI and each two minutes a scheduled ftp transfers the PGN to my website. The live pages on the website are automatically updated each 30 seconds, so they will display the new moves relatively fast when the PGN has been updated.

All this is of course not very relevant for the viewers, as it is perceived to be quite seamless. I have had some great help from Paolo Casachi who is the programmer of pgn4web (excellent tool for displaying chess games on the net)and Matthias Gemuh, programmer of the excellent ChessGUI.



There's a lot of discussion about copyright issues with all these different engines, some of them open source. What's your opinion on this? My basic opinion is that I will continue to include the engines I want to include, unless any of them are proven to be violating copyrights or otherwise proven to be a clone in a court of Law. I am not a programmer so I am in no way qualified to say that "engine A" is a clone or "engine B" contains too much code taken from "engine C" and so on.

I think open-source is the way of the future - an engine like Stockfish is considered (by the community) to be perfectly legal and it is super-strong, too. I am sure quite a few programmers have learned a lot from reading the source code of this engine.

What, do you think, could be interesting for regular (tournament) players, regarding this match? I would think that they could get some tips from the games played with (to them) familiar openings or by studying some of the endgames. If not any of this, then the overall quality of the games from a pure entertainment point of view.

Do you think top GMs should start using Houdini for their analysis? Can this make an important difference? I would never recommend just using a single engine for analysis, but I am sure that with this latest version of Houdini any top player could get a few valuable, additional ideas of an opening or a position. Worth to note is that in the match, Houdini won 12 games and lost 5. If one were to study the patterns in the games Houdini lost you might get a good idea of which positions it cannot handle that well and vice versa for Rybka.



Can you make a selection of the most interesting games for replay in our game viewer? First I will present game 1 of the match (note that all book moves end after the 10th move). Here we have a Sicilian where both kings are pretty exposed. Houdini first sacrifices a pawn, then another and then finally a third until Rybka suddenly finds itself in heaps of trouble. All this was done with no queens or any mating threats on the board. I still have problems understanding this game but it was surely one of the greatest games I have seen in a while. And that it wasn't played by a human makes it even more mystifying.

The second game is game 26 where Rybka in the end wins with 2R+2P vs Q. This is also a very nice game in my opinion.

The last game is game 37 where Houdini, as White, plays a move which really made the chat go warm. The move 43.c6!! was not really seen by anyone and I am still trying to grasp the depth of this move.

All in all there were several more great games, but also a few not-so-interesting draws.

Three games selected by Martin Thoresen

Game viewer by ChessTempo

Links

• TCEC website
• All 40 games in PGN