Strelka Chess Engine

Strelka (rus. Стрелка) is a computer chess engine for Windows, developed by Yuri Osipov. In total five versions of the program have been developed. The current version, 5.5, has support only one core. Now, Strelka is one of the strongest programs in the world,[1][2] according to several blitz rating lists[3][4]and the strongest in Russia.[5]

In May 2007, a new chess engine called Strelka (Russian for "arrow") appeared on the scene, claimed to be written by Yuri Osipov. Soon, there were allegations that Strelka was a clone of Rybka 1.0 beta, in the sense that it was a reverse-engineered and slightly modified version of Rybka.[10] Several players found Strelka to yield identical analysis to Rybka in a variety of different situations, even having the same bugs and weaknesses in some cases. Osipov, however, stated repeatedly on discussion boards that Strelka was based on Fruit, not Rybka, and that any similarities was either because Rybka also was based on Fruit, or because he had tuned the evaluation function to be as close to Rybka as possible.[11][12]

With the release of Strelka 2.0 beta, source code was included. Rajlich stated that the source made it "obvious" that Strelka 2.0 beta was indeed a Rybka 1.0 beta clone, although not without some improvements in certain areas. On the basis of this, he claimed the source as his own and intended to re-release it under his own name,[13] although he later decided not to do so. He also made allegations that "Yuri Osipov" was a pen name.

According to Victor Zakharov (Convekta company) in his review for Arena chess website: "I consider that Yuri Osipov (Ivanovich) is real name. He didn't hide it. However I can't state this with 100% assurance." And he also has some contact with Yuri Osipov for development of mobile platforms chess program.[14]

However, Fruit author Fabien Letouzey has clearly expressed in the open letter mentioned above that Strelka 2.0 beta is a Fruit derivate with some minor changes.[15]

Arrow engine written Osipov Yu . And . of Pushkino (Moscow region). In our first test, Arrow - the strongest Russian engine and one of the strongest in the world! Here he wrote about his program, Yuri, who works  as a programmer at one firm in Moscow: "I am writing about since 1983. history of the creation Arrows can start afar. Around 1986 I first became interested in gaming algorithms. No specific ideas were not, I just wanted to try make playing program. I chose to start simple tic-tac-toe (five in number), and this game was first tested the basic principles of the minimax and alpha-beta. Four years later, I decided to swing at chess, and start writing something simple . This program played a very bad - most imitated game. Gradually, the game program was improved, but then I threw it. 

And then, in 1996 there was a surge of interest in another computer chess. Modest Fritz written for PC, at the next World Cup surprise all became the champion, leaving behind such a monster as Deep Blue. I realized that the time has come when virtually any qualified programmer rather modest technique can achieve significant success. 
But I did not want to go back to the boring pretty alpha-beta algorithm. There was an idea to implement something completely original, and gradually formed the corresponding algorithm. Idea of the algorithm is quite simple - we bring a chess problem in the search for an extremum of a function defined on the set of points, and instead of busting trying to look in the most extreme of this promising area (something like descent method). The trouble was (as with all such algorithms), in constant stalling in local extremes, of which I could not get out. 
I made numerous attempts to fix something, but nothing came of it. 
And then I decided to go back to the old kind of alpha-beta algorithm and bring it to mind. By this time, accumulated a large amount of diverse information about this on the Internet, including open source. After reviewing all this, I discovered how perfected in recent years the alpha-beta. And I sat down to write, using essentially what was known to all. As a result, Arrow was born, which is quite unexpected for me was quite strong, though very imperfect.

By rum copyright explanations we consider necessary to say that Yuri Osipov wrote engine for Winboard a standard shell. At the final stage of Yuri finished the main Winboar -s command. During the week a number of forums in Russia and abroad actively discussed topic Arrows. Today authoritative experts Bryan Hofmann, Dann Corbit and Sergei Markov (Sergei S. Markoff) , who had the opportunity to get acquainted with the source files, acknowledged that the Arrow - the original engine. And I'd add that today it is one of the strongest free engines in the world, if not the strongest, and undeniably the strongest free engine in the CIS!

Interview Yuri Osipov from May 8, 2007 (published May 11, 2007) can be found here .

Latest news from Yuri Osipov. Jury resumed work on the arrow on this plan.

1. UCI protocol implementation with all kinds of time control. 
2. Weak pawns conversion. 
3. Displays the distance to the mat. 
4. Ability to change the size of the hash. 
5. Pondering. 
6. Milti-PV for the analysis of several options. 
7. Improved evaluation function, especially in the endgame. 
8. Transfer tables estimates of the constants in the hash, which would reduce the size of the EXE-file to ~ 400-500 KB

The plan is executed. Appeared Arrow 1.8 UCI! According to our tests gain new version of at least 50 points! Of course, we already have a new experience of a somewhat different style of play arrows, but do not want to impose chess fans point of view. Engine can download from our site! Unfortunately, the new version does not support the Winboard. engine plays at more than 2,800 unitsand is, hopefully, a strong free program in the world that exceeds the absolute most commercial software! At least this applies to the engine implemented for the 32 - bit applications that do not support very much hope that this is temporary, multiprocessor systems.  power game Arrow seems now surpasses many commercial strongest engines such as Fritz 10, Junior 10.1, Shredder 10.1 and more!  

Christmas gift chess fans and programmers all over the world did Yuri Osipov! A new version of the famous Arrows 2.0 Strelka 2.0B) . Source files are now publicly available engine! The new version, according to preliminary estimates Yuri, added at least 50 points! New version as version 1.8 only supports UCI protocol and can be connected to the shell WinBoard only using polyglot.

Download the archive file with zapusknoe now includes engine and source files, you can from the page DOWNLOAD .

Author's comment about a new version of Arrows:

"After a long break and after the tumultuous events that have occurred in the world of computer chess lately, I decided to publish the latest version of Arrows. This publication was preceded by a lot of work, but it was conducted in a private mode. were made several dozen versions of series 3 and 4. Benchmark version number is 5.  Innovations in Strelka 5 quite a lot. Most important innovations - in the evaluation function.  Unfortunately, not all of the planned managed to make and test. 5 Because of this Arrow can sometimes give strange results, especially odd value may be position estimates. This is due to the fact that the assessment is based not only on the basis of the current position, but also as a function depending on the chain of moves that led to this position. weights of different parameters of the engine are not subjected to rigorous testing due to lack of time, so I not much to ask for kicking strange results Arrows. Like previous versions of Arrows, the new version is 32-bit and single-processor. Therefore, it is difficult to compete with modern 64-bit and multi-processor monsters. But in his weight class Arrow 5 is quite competitive.


The latest version, prepared by Yuri Strelka 5.5 (32 UCI). With the release of the 64-bit version 5.5 Arrows Yuri did an updated compilation of the 32-bit version! According to the latest version of the author's assessment Arrow 5.5  surpasses its predecessor Arrow 5.1 by 40 points! Now it remains to wait for the multiprocessor version of Arrows!

The text of the second interview Yuri Osipov 21 October of 2011 can be viewed here .


Playing strength

As of version 5.0, Strelka includes 32-bit and 64-bit uniprocessor versions. In rating CCRL 40/40 from 17.08.2013 chess program Strelka 5.5 64-bit has 3115 Bayeselo.[6][7] In blitz-rating CCRL 4/40 from 24.08.2013 chess program Strelka 5.1 64-bit has 3137 Bayeselo.[8] In blitz-rating CEGT 4/40 from 28.08.2013 chess program Strelka 5.0 x64 1CPU has 3003 Elo.[9]