Beyond the 3000 Elo barrier A glance behind the scenes of the Rybka chess engine by HARALD FIETZ t the end of 2005, the worked in the computer field. My looked very promising and scary for world of chess computers mother is also a trained mathematician. the opponent when I played them, but suddenly changed when an I have two younger brothers. We moved in a post-mortem Rybka sometimes engine with the name back to Prague when I was three weeks revealed them as crazy blunders. I A of Rybka appeared from old and stayed in the Czech Republic believe that using Rybka can help to virtually nowhere. At the prestigious until I was 11 The whole family develop an intuition about which International Paderborn Computer moved back to the USA at that time. I sacrifices actually work. For sure using Chess Championship the new program studied computer science at MIT Rybka has some influence on my by the American developer Vaclav (Massachusetts Institute of Technology) openings – I think that my repertoire is Rajlich – whom everybody simply calls near Boston and worked as a software getting much stronger thanks to my Vasik or Vas as his first name – won developer at Texas Instruments (Dallas, work with the engine.” a clear point ahead of established USA), Triada, a company specialized in machines such as Zappa, Spike, data compression, (Ypsilanti, USA), A programmer’s everyday life Shredder, Fruit or Jonny. Out of the Ford (Detroit, USA), at the Environ- and visions blue, Rybka skyrocketed to the top of mental Research Institute of Michigan, the Swedish computer rating list, which was developing radar imaging However, the improvement of a which had been regarded for a long systems (Ann Arbor, USA), and Option, sophisticated program also requires a time as the equivalent of the FIDE a leading company in the field of lot of support from other sources: rating list in the chess computer sector wireless communication technology “There are tons of people who are (cp.http://web.telia.com/~u85924109/ss (Adelsried, Germany), over the last involved in the project in various ways. df/). However, chess computer experts thirteen years. Now, I am working full- My partner Convekta Ltd. handles the now regard the results of other time on Rybka in Budapest, Hungary.” business and marketing and develops test teams as more reliable (e.g. He came over to Europe mainly in order graphic user interfaces on which Rybka http://www.husvankempen.de/nunn/ or to pursue his chess career after he was runs. Jeroen Noomen from the http://www.computerchess.org.uk/ccrl/ fascinated by the royal game Netherlands writes the Rybka opening 4040/). Depending on hardware, Rybka comparatively late: “Chess was quite book – this is an extremely competitive surpasses every other program by 60 big in my family, mainly thanks to my sub-discipline of computer chess which rating points at least, and is the first grandfather on my father’s side, who has quite an impact on engine results. engine which has established itself was a very enthusiastic chess player in My wife Iweta uses Rybka constantly beyond the 3000 Elo rating barrier. the Czech city of Tabor. I started to play and gives me feedback which I use to Among top players, Rybka is tournaments quite casually at first, improve the engine. The Polish GM increasingly regarded as an added value when I was about 20, and then went Michal Krasenkov is a member of our to the engines they traditionally use; through a big chess phase in the period team in the freestyle events. Christoph Alexander Morozevich even gave 1997 through 2003 or so. Now I am an and Felix Kling from Germany have Rybka the highest score in his voting international master.” Like most other developed the Rybka web site for the Chess Oscar 2005 and put ‘chess travellers’ he chose Budapest as (www.rybkachess.com). In addition, forward allegations that the ‘Topalov a hot-spot for ambitious chess players. there are dozens of other testers and test team’ might have used this tool for However, this also turned out to be the groups around the world who give me cheating activities. place to find his private future: “Around useful ideas and test results, and who Therefore, it is high time to get first- 5 years ago I met Iweta Radziewicz at a create the objective test environments hand information from the man behind tournament in Budapest, and we got for chess engines, without which the machine. The place to meet Rajlich married on August 19, 2006 in computer chess itself would not exist. was the Hungarian capital of Budapest, Piaseczno near Warsaw.” The Rybka project would hardly and the visit also offered a unique The now 26 year old Polish be possible, at least in its current opportunity to peek over the shoulder of international used her years of study to form, without all of this help.” The his team in order to watch the man- continue her junior achievements at the fundaments can be traced back to his machine interaction during a freestyle top of the world ranking. Besides teenage years: “I’ve been programming qualification tournament. finishing her diploma in psychology in my whole life, I wrote hundreds of 2005 (with a thesis on “Risk perception programs before I even got to college. From computer freak and assessment among chess players”) These programs included a Connect-4 to chess couple she got the male IM title and one GM program (a two-player board game in norm so far. Now the five times Polish which players take turns dropping discs In a few years time Rajlich’s career women champion, who won her latest into a vertical grid, with the objective of might be described as a typical title in March 2007 in Barlinek getting four of one’s own discs in a American rise from rags to riches. (Emanuel Lasker’s place of birth), is line), this was my first experience with However, this time the American has ‘the main tester’ of the Rybka program game-playing algorithms.” The idea left the States to try his luck in ‘old’ and assesses its values from the of creating a chess program for Europe. He describes his life-long tournament player’s point of view: professionals combined Rajlich’s hobby shuttle across the Atlantic: “I was born “Rybka is quite an objective analysis and skills he learnt at university. in Cleveland in 1971 where my Czech tool and tends to defend very well, so Nevertheless, it is not easy for him to parents were studying at the time. My perhaps I learnt to sacrifice more define a chess programmer’s profile: father is a mathematician and later correctly. Many times my sacrifices “The main qualification is kind of 18 CHESS May 2007 vague – it’s a sort of semi-mathematical you a model position in order to what he suggests. In the opening and thinking ability which is hard to pin demonstrate this function. early middle game as well as in the down exactly. Some people just have it, XIIIIIIIIY endgame we tend more to overrule the others haven’t. Of course, it also helps Rybka engine more often than in the to have software development skills and 9r+l+-trk+0 middle game. White’s moves g6! and chess skill. My main interest in 9zpp+-+qzp-0 h5 in the game Rajlich-Intragrand are computer science has always been 9-+p+p+-+0 human discoveries (included below as artificial intelligence, for instance, at 9+-+p+p+-0 part of the analysis of Rajlich- ERIM we developed algorithms to Kingscrusher). identify features on radar images, etc. It 9-+-zP-zP-+0 Furthermore, we are using Rybka to had always been in the back of my mind 9sN-+-zP-zP-0 go deeply into tactical lines. If the that some day I would write a chess 9PzPP+-+K+0 position is rather strategic (I mean with program. Finally, in January 2003, I got 9tR-+Q+-+R0 little tactics) we try to choose a plan. started, and immediately stopped doing For instance, in the game of Poweroff everything else.” xiiiiiiiiy with the white pieces against Rajlich in Now the daily life of this Washington The above position is meant to the final of the 3rd freestyle Redskins fan – and of the NFL in illustrate the idea that positional competition, we had a very difficult general – looks pretty much all the evaluations change as the search gets position, and in order to save the game same in their small two room-flat in the deeper. Rybka’s static evaluation has no Michal came up with a clever idea of centre of the Hungarian capital, some trouble understanding that the bishop exchanging knights for the cost of 200 meters away from the Danube and on c8 is a bad piece, so this bishop will another pawn. The game transposed the famous Liberty bridge: “It very be consistently reported as a bad piece, into opposite-colour bishop endgame much depends, but Rybka development regardless of how much searching is where Poweronoff (who played as an goes through cycles which are roughly done. This will be indicated to the user unattended Rybka) had two pawns as follows: 1) get a new idea; 2) refine via some sort of colour coding of the more. I don’t have to mention that the idea, maybe make some preliminary piece or the square it sits on. The knight sacrificing a pawn for an idea which experiments; 3) initial implementation on a3, on the other hand, is very appears in 20 moves later in a drawn of the idea and 4) testing.