Reports | March 29, 2010 18:54

Chess engine controversy

Controversy over chess enginesIn this week's The New Yorker, James Surowiecki calls Apple's launch, next week, of the expensive iPad 'a fundamental gamble, namely that people will pay for quality'. In today's world, free (digital) stuff is indeed so easy to get that it's increasingly difficult for companies to make money with new technology. Think downloading movies and music; think installing a cracked version of Office or Windows 7. But what if something of equal or better quality can be obtained legally and for free? Like... a chess engine?


Like almost all serious chess lovers, here at ChessVibes headquarters we're big fans of the Rybka software, which is relatively cheap and will for sure be your strongest chess coach ever. Recently, however, a chess engine was released on the internet which is claimed to be even stronger than Rybka's latest release... and it's totally free. Welcome to the world of open source software, and its many complicated discussions and controversies.


Firebird is an open source chess engine developed by a team of anonymous Russian programmers who call themselves the Decembrists, after the well-known uprising in Russia in 1825. It's part of a whole family of chess engines called IPPOLIT. It was released in October 2009 with its source code. In other words, the guys who made the program didn't care if others found out how they did it - they share their 'code' with the whole world. (Update: See Vincent Diepeveen's lengthy comment for more details on the background on the Firebird-programmers. As Russian translator Paul Janse notes, Ippolit Matveevich Vorobyanov is the name of the anti-hero in Ilf and Petrov's famous novel The Twelve Chairs.) Firebird is slowly but steadily gaining in popularity, not only with hardcore chess computer fans but also with strong chess professionals. The reason? Not only is it completely free, but it's also allegedly stronger than Rybka. Various comparisons on the internet between Rybka and Firebird have suggested that Firebird may be some kind of improved Rybka, although nothing is very clear here, either. (According to a small survey among the ChessVibes editors, we found that Firebird does seem to reach deep ply levels a bit faster.) At the recent Amber tournament in Nice, ChessVibes asked two leading Dutch grandmasters, Jan Smeets and Erwin L'Ami (who happen to be on Veselin Topalov's team), whether they knew about the Rybka/Firebird developments, and what they thought of it. Here's how they see it:

Smeets: I read on some forums that such a clone existed, I think this was in October last year. I think I read it at the Rybka Forum. However, there it wasn't allowed to mention the name, but if you Googled it it was easy to find. At that point it was Ippolit. First it was Ippolit, then Robbolito, then Igorit. Robbolito was a one-core engine, but quite a strong one-core engine, so you could run it simultaneously with other engines. Igorit was the first multi-processor engine but I think that one was a failure. And then came Firebird, which was a combination of Robbolito and Igorit, and this one was good. I use many engines, because it's good to vary. L'Ami: One day I entered his hotel room, during the Corus tournament, and I saw all these strange, crazy names I had never heard of. But now I know that currently everybody uses them. Smeets: Yes, many, many players use them. It's also a popular subject on the ICC for example. But it doesn't make a big difference, you know. These programs are so strong these days. I think they're all playing at 3300, 3400 level so fifty points weaker or stronger doesn't really matter.


So what's the deal with all these new engines? Is one really stronger than the other, and how does it matter? Well, here's where the controversy begins. Right afer Firebird was released, a statement appeared on the Rybka forum site (Smeets also refers to it) in which Rybka's creator, Vasik Rajlich, officially declared:

There was an open-"source" (using the term loosely) clone of Rybka 3 released in the spring. Unlike the last time, there was no real attempt to hide the cloning - the hackers were even kind enough to keep me updated via email.

Rajlich alludes to a previous confrontation with Russian open source progammers - or 'pirates' as Rajlich calls them - back in 2007, when the open source engine Strelka was released, which was, according to the Rybka team, suspiciously similar to many features of the Rybka 1.0 engine. Here's the relevant background from the Wikipedia-article on Rybka:

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. 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. 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.

Rybka & Fruit

An important aspect of the whole argument is yet another accusation, this time from the Russians, namely that the first release of Rybka was itself largely based on the open source engine Fruit, which was released in 2006 and is now a so-called freeware program (not to be confused with open source software!). In a lengthy, very interesting video interview Rajlich gave to Nelson Hernandez last year, he didn't really answer the question as to which open source programs initially influenced the development of Rybka the most:

Hernandez: What chess engines in public domain, when you got started, had the biggest influence on the earliest versions of Rybka? Rajlich: Well, actually I started in a kind of strange way. I printed out just about every single paper there was to print out about computer chess; all these academic papers. A lot of them are interesting, a lot of them are just really relevant, actually. (...) So I kind of started to work through that, that was how I started. Probably it's not the most efficient way to do it. Probably the most efficient way is to take an open source program - at that point it would have been Crafty - and just kind of go through that. And I gradually worked around through that. (...)

Those interested in the gory details of the allegations might also want to read the IPPOLIT Wikipage, which includes statements such as:

  • Rybka's piece square tables are generated from the same code as Fruit's.
  • Rybka's pawn evaluation is virtually identical to Fruit
  • Rybka's "pattern" evaluation is virtually identical to Fruit's

These are, well, interesting claims, which suggest deep code-researching, but unfortunately, the website contains mostly stuff like:

In the this the prominence of the Revolution versus unto the Capitalists obliges with the stroboscopic clarity unto the final victory. For the Revolution: anonymous for with the philosophics. For the Capitalists: anonymous or plus known (too), in with the conveniencings.

Such incoherent nonsense makes it considerably more problematic to take the claims from the IPPOLIT team serious, and it's probably one of the reasons why Rajlich is so fed up with these guys. Anyway, the net result of all this is that the IPPOLIT-article on Wikipedia has now been deleted and accusations of censure and even some far-fetched global conspiracy theories are suddenly all over the internet. On the Rybka forum and even on other chess computer sites, all discussion of IPPOLIT software are deleted or banned, causing even more anger with the 'Decembrists' and their supporters. And they seem to have a point, as this aborted discussion on shows.


One thing that's clearly lacking is concrete evidence from the Rybka team that Firebird is, in fact, a true clone of Rybka - something that is, of course, required in the case of any serious accusation. But so far, the evidence has not been presented in a coherent way. In an intriguing and generally polite discussion on the forum of, one defender of IPPOLIT react as follows:

[Rajlich] claims that the authors were in correspondence with him the whole time they were doing this. Show us the correspondence and maybe I will believe. BUT, (and thats a big but) reverse engineering is not illegal. For years there have been forums that have been trying to figure out how Rybka works by its playing style. That is also reverse engineering. All [Rajlich] is saying is that [IPPOLIT] uses ideas similar to Rybka. He can't or won't prove that these ideas are even in Rybka. And even if they are, Rybka is a five year old program.

The Rybka team itself apparently doesn't want to spend much time about it. In a brief reaction, Rajlich wrote to me: "These are all just decompiled Rybka 3 clones. It's pretty obvious from the Ippolit sources, any programmer will tell you the same thing." As a programmer myself, I must say I find his point of view understandable, because I know how hard it is to make good code, and how proud a well-written script can make one. Rajlich is also, obviously, tied to a highly successful commercial product with links to other companies and sellers. (You've guessed it - here's where the conspirary theories start to unfold.) On the other hand, it would enormously help resolve the controversy if some real evidence was presented by the Rybka team. This could be 'code snippets' (relevant fragments of code), or other striking silimarities in design, or even, as the above commenter suggested, quotes from correspondence with the IPPOLIT programmers. The problem, I assume, is that Rybka's code is not open source, and showing it as part of evidence against pirates may in turn compromise its integrity - and this time, it wouldn't be stealing. This puts Rybka in an unpleasant Catch-22 situation, which was no doubt gleefully foreseen by the Decembrists. But even apart from any technical discussions - what if Rajlich is right and Firebird is simply a Rybka clone - a product of piracy, that is - only stronger? Should we all stop downloading it just because it wasn't manufactured in an entirely 'fair' way? As another commenter on the forum muses:

If they absolutely ripped off Rybka, then I would be happy to remove Firebird from my computer and purchase Rybka 3. No big deal. I've got the money and want to support software developers, as I have always done in the past in the field of music. Music software is far more expensive. Several of my music programs cost between $250.00 to $500.00. One product requires a $100.00 upgrade fee each year to stay current. I don't use cracked software.

Not worth it

That sounds very noble, but how realistic is it? Perhaps hardcore computer programmers have some sense of professional ethics, but what about pro chess players like Jan Smeets and Erwin L'Ami? Can they expected to be that honest as well? Aren't they right to be just interested in the best available chess engine and compare them, use them all to their own advantage? Here at ChessVibes headquarters, we're in serious doubt. We're very sympathetic of Rybka's cause, simply because it's such an outstanding and cheap product. Rajlich wrote to me he very strongly believes in having a positive message:

Rybka 3 doesn't even have normal copy protection. Future versions of Rybka will be available over the internet - users will log into PlayChess or ChessPlanet [or ICC or FICS - ed.], and their analysis will run on remote machines, like with cloud computing. This has a lot of nice properties - continually updated Rybka versions, possibilities for shared analysis, hardware power available from traveling devices like Pocket PCs, iPhones, flexible hardware availability, etc. It also has the side effect that it stops all software piracy - these now-ancient problems from two years ago won't be repeated.

That's great news (and the idea of online engines is controversial in its own right) but it doesn't answer the moral dillemma whether we should use potential clones or not. We'd really like to give Rybka the benefit of the doubt, but at the same time we think that as long as Rybka's accusations are not based on concrete evidence, using Firebird as an interesting alternative isn't morally wrong necessarily. After all, as Surowiecki writes in the same New Yorker article, information (or, in our case, evidence) is also an aspect of quality - increasingly so, especially in our modern digital world. Perhaps most importantly, Jan Smeets makes an excellent point when he says it really doesn't make that much difference, unless you're going to hold matches between the two programs just for academic purposes. In practice, who cares if a 3300 rated engine or an 3350 one is assisting you in analysing your games? Such a trivial difference is simply not worth it to award potential pirates and mistreat the original programmer. We hope the whole matter will be resolved soon.

Arne Moll's picture
Author: Arne Moll


El Guest's picture

the links are a little outdated Angels 77 promotes IvanHoe freely , as we do opening books for computer chess
We suspect Vas waits untill after April 22nd ( Stalins day ) which may hail the final mourners leaving Deep R.I.P$ykba3 mourners leaving its creamation ,before he dares raise $ykba4 from its ashes

Neeraj sharma's picture

good to have a free engine source code atlest everyone use it and play and analysis from it this way the chess game is spread far and wide and reach every people unlike rybka using money for game......i always suport programmer who contributed this firebird ,ivanhoe,ippolit,robbo...if vas claimed it to be clone why cant vas explain from which engine he too cloned rybka??????? Its not abt chess engine vas is taking abt superiority of his and money over others chess programmer ..but he should learn that he is not the only programmer in the world and his fish can also be swallowed by another big bird or fish....why cant he came out on public debate and prove his claim of clone simply beacuse if u sater one finger on other u will find one fist staring on you.......bcoz he is also using some cloned programe like fruit to make rybka3 ...The computer chess engine is not come in four yrs time its history is long and any improvement of it is based on the underlying knowledge available ..vaas has not discovered or invented he just improved the chess engine and iggorit and firebird or ivanhoe is also improving their chess engine matter which source code and wat engenieering ..atlest they are providing it free to every people who luv playing chess and improve their i truly support all the improvement and advancement this open source engine and giving every individual a change to PLAY THE GAME AND NOT FOR MONEY...

alex's picture

I add the engine (fruit 2.3.1) in my list of fritz 10 programme's.
Then I organised a match (a blitz (50) and a rapid( 10) ) between Fritz 10 and fruit 2.3.1.
But the most games (with blitz and rapid) where won by fritz 10, how is that possible??? I read that fruit a clone of Rybka is, but my fritz is still stronger.
I havn't done anyting with the parameters, ....

Felix Kling's picture

Mmh. Actually you get the same problem as the big chess fora. Now this article is the start for people to spread clone links and so on :(

Pal G.'s picture

Like Smeets says, the ELO difference between the strongest engines is trivial. Why not download and support engine authors whose license is, as Chessbomb says, the least ambiguous. Therefore I use Glaurung, Stockfish, and Fruit all day long with no guilt or question or concern for who and who isn't getting paid or stealing.

As Lance Armstrong would say, "It's not about the engine". It's about Chess.

Ippolit Supporter's picture

You cannot provide proof because you know deep in your heart that the IPPOLIT family engines (Robbolito, Ippolit, FireBird, Iggorit, IvanHoe) are not clones. All you can do is give false accusations, and you cannot even defend yourself, you cannot show anything to prove your false claims. I don't understand why other people still believe you. The good thing is, lots of people everyday are starting to believe that Ippolit engines ARE NOT CLONES (Oh yes, even the die-hard members of your "Rybka Religion" are beginning to see the light to the right path) Why? I guess that is your fault because you cannot provide any proof to support your claims. As we all know, a lie is always difficult to prove.

test's picture

God forbid people find the website Google because who knows, they might use it for, you know, searching stuff?

And where's the proof?

Arne Moll's picture

@Felix: yes, there are people spreading links to open source software (though not all of them clones, surely), but there are also people talking sensibly and sharing valuable information, which could even lead to change in or better understanding of the current situation.
Felix, you sound like a reasonable person. I don't see how you can oppose sharing objective information, be it in my article or in the comments - opposing this sounds pretty medieval to me. Or, as Jack Nicholson said in A Few Good Men: "You can't handle the truth!" Is that really your point of view?

SanChess's picture

Well, I bought Deep Rybka 3/Aquarium but still use a lot of free engines for analysis and tournaments. On a practical level the controversy around clones has nothing to do with the interests of the average users. We just want the best engines and all the more if they can play interesting chess and threaten Rybka's hegemony.

alpha123's picture

Hello Felix..... I believe we've met...... I was banned on your forum for speaking the truth.

I have yet to see the proof from you and your God Vas that IPPOLIT & Co. are clones. Yes, I said the name to your face....... you cannot ban me here, too.

Present the evidence Felix, I am waiting for it. While you can avoid making a fool of yourself by running and hiding, that will hardly continue to brainwash people that IPPOLIT, RobboLito, Iggort, IvanHoe and relatives are clones of your beloved Rybka.

And to remove the doubt, Rybka is based heavily on Fruit. Code was copied. The evidence is here:
You have been trying to hide it, to squash it, to deny it, but it is there.

Arne Moll's picture

@alpha123: I've allowed your comment because I guess the link you provide is relevant to the discussion, but please watch the language, okay?

goodchess's picture

we are not in China!

Either we get a proof or this fighting agiainst the freedom of speach and trying to block objective dialog must stop right now!

For sure I wont read any website where freedom of speach is not honored.

Mamago Mamago's picture

Is Felix talking of Vasik who allegedly cloned Fruit , sold it as Rybka and made a decent amount of money from it ?

Ippolit Supporter's picture

I am glad to see that I AM NOT THE ONLY ONE here. :)

JM's picture

What are you worried about? Arne Moll took the most sensible stance not to censor anything. Freedom of speech also means that Felix Kling of the Rybka team is free to give his opinion.

Personally, I agree with test that it's word against word. If Vincent Diepeveen is correct that you don't simply pull a chess engine like this out of a magic hat, then test is correct that the same can be said about Rybka. Some of the new engines may resemble Rybka, but nep makes a good point that the same could be said about Rybka as compared to Fruit. Contrary to Felix Klein's opinion, the legal case doesn't seem clear to me at all. As Ayumi mentions, the question about the legality of reverse engineering has no clear-cut answer. (Is the Rybka team actually accusing the unknown programmers of code stealing or reverse engineering? )

At the end of the day, as an end user, I don't see much reason to condemn without proof. Maybe it's a clear-cut case of 'stealing' from the insider point of view of the Rybka team, but from an independent point of view, I haven't seen any proof. @Felix Klein of the Rybka team: I'm sympathetic towards the efforts of the Rybka team, but please consider the following. All your statements so far may be very objective from your point of view, with your inside information about the Rybka code and so on. For an outsider without this information, your arguments are neither verifiable nor independent.

orange.engine's picture

Well, I found this article very informative. It is good to have these kind of information sources that can't be supressed by rybka team(although I see they had tried to supress some info here, thanks Arne Moll for not allowing that) , a lot of comentaries would have been already removed in some "very importan chess forums"

I'm interested in facts. Up to now, rybka team have not released any proves supporting what they claim to be rybka's clones. On the other hand, the ippolit family has released the codes. And the codes are there for anyone to use and improve these engines.

The onlyone statment that I have seen against ippolit family is that: Well, they're better than rybka, but, who is the author????, their home page seems like a joke, ok, so the onlyone explanation is that they're rybka clones.

That to me is unacceptable. And, by the fact that it's clear that proves from the rybka team are missing (and I think that's because there aren't any) I don't get it why these strong engines are banned from computer tournaments and in places like playchess. Ok, wait a minute, indeed it's very clear! It's all to do with money interest.

So I'll still be using ippolit family engines and firebird also, and spreading the word that all these are clearly stronger than rybka.

Felix's picture


"If Vincent Diepeveen is correct that you don’t simply pull a chess engine like this out of a magic hat"

You mean like Vas did with Rybka 1.0 beta ? pulled it out of a magic hat um.. fruit basket more likely.

This is no different,

Get your strongest chess engine in the world for free now:

Felix Kling's picture

There is some problem when saying that downloading and using those programs is legal, as I said, even if they provide source code ("open source"), it's still a violation of copyright and the licenses they use can't be applied.

I'm no programmer, but it's obvious that those are no original engines when you use your brain. Why should a serious programmer use fake names? Would a serious programmer investing a lot of time create such a website? Would he act like this?

Additionally Vas stated that those are clones and there's no reason why he should be lying.

I would call myself rather objective in this case, since there's no "official opinion" for the Rybka team and any team member may think and say what he thinks is right. My position in this matter is based on logical thinking and drawing conclusions from facts. I know that people tend to deny reality, but if you think about the whole subject and don't come to the conclusion that this is basically piracy, I would like to hear your arguments. A naive approach like "there has to be a 100% proof by a court" doesn't apply (this way you could use any clone), but if you would provide me with a good, logical reason why the "authors" of those engines use fake names (my first argument), I would most probably change my mind.

The Riddler's picture

Well Felix, first of all, when you say that you "used your brain" implicity you're saying all the other (not thinking like you) don't use it at all. Congratulations for your modesty genius!

Second, a valid logical reasoning has the form: (True ^True^True)-->True. But, let us analize your "logical thinking":

"it’s obvious that those are no original engines when you use your brain". This premise is False, maybe you used bad your brain, or maybe you had a bad brain, or maybe you don't know how to use your brain.

"Why should a serious programmer use fake names? Would a serious programmer investing a lot of time create such a website? Would he act like this?" This is not a premise is an interrogative statement, it is not valid for sustaining a logical thinking.

"Additionally Vas stated that those are clones and there’s no reason why he should be lying" This is another statement without logical value, again not valid for a logical thinking.

"My position in this matter is based on logical thinking and drawing conclusions from facts" this is False you don't use logical reasoning, you "used your brain" and it is the beginning of you completely wrong reasoning.

anderson's picture

Felix Kling => "I’m no programmer, but it’s obvious that those are no original engines when you use your brain."

Felix please provide evidence as alpha123 has asked , it would really be helpful to use as your an official representative.
Alpha123 has also provided very interesting information about the Rybka's evaluation functions "taken" from fruit.

What is your opinion on this?

Also in your opinion will future Rybka versions use code/ideas from the current Ippolit family, will it perhaps "lend" ideas from Stockfish? since this code is freely available.

And then the think that bothers me most, how would we know? The truth is in the end I might end up buying a finely tweaked stockfish re branded as Rybka 4

This is why it is hard to dispute full disclosure.. show us the code and we will believe you.

blueofnoon's picture

"Why should a serious programmer use fake names? Would a serious programmer investing a lot of time create such a website? Would he act like this?"

I myself know lots of open source programmers and many of them use fake names. The reasons vary, but I can say what is a serious job for one person may be just a pastime for another.

In my country a lot of great free/open source software are indeed released by anonymous authors. They are actually working for companies like IBM, Sony etc and don't want to reveal it.

I don't know the exact reason about this case, but I don't mind using software by anon authors at all.

KingTal's picture

@Felix Kling:
If you say that there is no reason why Vas should be lying makes logically no sense, because he makes money with Rybka and if there is another engine that is better than that and its even free, so why should people buy his product? Its not good for his sells, so of course he would like to see the IPPOLIT engines dead and thats imo the reason he calls them clones, even if there isn´t any reasonable argument that they are Rybka clones...i also don´t see any reason why they should use their original names..they aren´t trying to make money with their engines like Vas does.

You can say but that is not fair because the Rybka team is so hard working and so on...but let´s see it objectively. Since Rybka 3 dominated the market and there wasn´t any competition on the chess engine market, no really progress. It makes sense, because there is no reason for Rybka team to improve their engine as long as its on top because its idea is to make money out of it and it doesn´t make sense to bring a more better programm as long as you can make enough money with that. It´s about milking a cow. So it´s good for the market because there is competition now and maybe finally they will start to improve their rybka engine and bring a better one IPPOLIT engines are open source i´m sure they will take some ideas out of it, i´m very sure. It´s all about marketing strategy and milking cows that´s what the capitalistic system is about my friends and i think everybody does know that.

alpha123's picture

Felix, I have a few questions for you:

Why don't Rybka and IPPOLITs have identical/very similar evaluations in most positions??

How did the anonymous authors manage to decompile Rybka 3, make that code compilable (very hard, decompilers definitely don't generate code that can be recompiled immediately) and somehow manage to improve it by ~60 elo in blitz and ~40 elo in long t/c.

I think Vas has mentioned that supporting bishop underpromotion would require several changes to data structures. I assume that the IPPO dudes, with their extremely messy decompiled C code, found those structures and modified them to support BUP?!?! Seriously, have you ever even tried to decompile something as complex as a chess engine and make changes like that?????

On Rybka/Fruit:

Something about Rybka smells fishy... or rather, fruity..... even if Vas only took ideas, the isolated pawn eval in particular I found remarkably similar, plus the passed pawn eval, the piece eval, um, well, pretty much the entire eval. Oh and the inline strtok() in the UCI parser. Vas didn't have to do that. In fact, I can't think of a reason he would. Except, of course, because the UCI parser came from Fruit......
Even if this is all in Rybka 1.0 beta, Dr. Robert Hyatt has mentioned repeatedly that you don't rewrite a program as complex as a chess engine randomly. Crafty 23.2 still has code from Crafty 1.0. I tend to agree with this, unless, of course, Vas tends to lose his source code files and has virtually unlimited free time......

kingliveson's picture

You can download Ivanhoe and tablebases here:

If Mr. Vasik Rajlich and Rybka team ever provide proof that Ippolit >> RobboLito >> Igorrit >> IvanHoe are illegal programs, they will be removed from the server. We've looked at the matter since October 2009 and have yet to see a grain of evidence suggesting these programs are not legal. They are legal to use and distribute.


test's picture

I found some interesting quotes from program authors:

Naum (current # 2 on the CCRL 40/40 Rating List)

Aleksandar Naumov: I work on Naum only at work when I am bored ...

The 1.6 is the first version after 1.2 that I worked hard on (probably 6-8 hours a day while at work :), because I felt that many competing engines are closing in. ...

I usually don't have time to go over Naum's games, because I can't have chess board on my screen at work :) (I work on Naum at home only during vacations) ....

I think that open source programs provide shortcuts to some authors, and I would be happier without them. On the other hand, nothing can replace experience and knowledge you get when you do something yourself rather then just take it from other person's code. You may be able to create a strong engine quickly, but you will never make the top engine that way. Nothing can replace creative thinking. I think a good programmer with chess programming experience shouldn't have any trouble understanding other people's code. I took a quick look only at the search algorithm of the Fruit and Glaurung. Never looked at Phalanx code. Actually I would like to know why is Fruit so damn strong. I didn't see anything special in its search algorithm, so it must be the evaluation. I really have very little interest in other people's code. I have so many ideas of my own that it will take years before I run out of them. I have a great respect for early engine authors (Phalanx, Arasan, Comet and Crafty come to mind). There is so much info about chess programming right now (even without the open source programs) making it much easier to create a strong program.

Stockfish, 3147 ELO, free, open source, current #3 at the CCRL 40/40 Rating List)

Tord Romstad: There are no plans of a commercial Stockfish. Why shouldn't it be free? All three of us have regular jobs which pay our bills; computer chess is just a hobby.

Marco Costalba: People is slowly realizing that opening the sources does not make your engine weaker and if it _could_ make other people's engine stronger the link is not direct nor trivial. Ippo sources are out from almost a year and all the biggest engines have released their new versions _after_ Ippo was out. But still no engine, commercial or not, has reached that level of strength and you can bet _all_ the top engines author have looked at the sources.

orange.engine's picture

How long does it takes comment approval????? Or may be I have to edit my comment, can I have it back??? You have may e.mail. Thanks in advance.

brabo's picture

There are different ways to get somebodies code besides decompiling. One is just directly breaking in on the computer where the real code is stored. Certainly in big teams it is extremely difficult to avoid leaks to the outside world. Computers get stolen, people are a bit too much open with so called friends,... A disclosure agreement which everybody of the team signs isn't a full guarantee.

Felix Kling's picture

@anderson: Only Vas can answer those questions, again, I'm no programmer.

@blueofnoon: In this case writing such an engine would be an incredible amount of work if you would start from scratch. Wouldn't that make it unlikely that the author uses fake names? This can't be compared with little programs.

@KingTal: See my first argument: Why should anyone who has to work like hell to create such a program want to use such childish fake names? Which logical explanation could you offer for this?

@alpha123. Easy. They added quite some stuff to try to obfuscate the cloning, some tables Larry added to Rybka are slightly modified and such things, some algorithms are added, some are removed. It's actually easy to create an engine with totally different output. About the big effort: Well, it's not the first time. See Strelka. About the UCI parser: I'm no programmer, there may be classical examples or not many alternatives for that. However, such things can hardly be considered real inventions of a program. About the evaluation tables: I don't know any details about it. But I don't see why I should trust Mr. Hyatt more than Vas. Afaik Fabien never did such accusations and everything seems fine for him, so even if programmers took stuff from Fruit (and it's clear that all major programmers had a good look at it) I don't see a reason to consider any modern engine a fruit clone. again, I don't know the Rybka sources and the only one who could answer that question is Vas.

orange.engine's picture

Felix Kling: Could you tell Vas that provide some aswers here, due to the fact that it seems tha you can't porvide them for us. Thankyou

El Guest's picture

Speak your min,,,,,,,,,,,,,,,,,,,,,,,,,,,,,why you only censor me

Arne Moll's picture

@orange.engine: the answer is it takes as long as the time we need to get some sleep!

@Felix: the fake name thing is really quite irrelevant. There are countless reasons why someone wouldn't like to reveal his real name. Privacy is an obvious reason, (lack of) reputation another one. Or someone might just enjoy creating as much confusion as possible. Some of the world's most famous artists from the past have for one reason or another prefered pseudonyms. This has only increased with the arrival of the digital age.

I am equally surprised by your statement that Vas has no reason to be lying. To play devil's advocate: this is of course what the Republicans said about Nixon right before Watergate. In fact, if we follow the logic of some of the commenters on here and on other forums, the fact that Rybka is partly derived from Fruit and that some open source programs are now challenging Rybka's market position seems an excellent reason to lie. Not that I'm saying that this the case, of course, but you can't rule it out because you happen to be on Rybka's side. This is why some concrete evidence would be so helpful. That demand is really quite reasonable, even if it's expressed by persons who lack manners or prefer to stay anonymous.

KingTal's picture

@Felix Kling:
I don´t understand your "argument". It´s clear that these guys want to express themselves in a humorously and provocating way. They are surely not a company so why use serious names, they probably want to stay anonymous. What´s the problem about that? They don´t need to bring their names as they don´t want to sell a product and make marketing so why need to make it such serious?

You must look at what people are doing and not what they might say, people talk a lot of stuff. I see that they did good engines, the best at moment and i don´t see any proof that this engines are cloned. You or better said Vas is now in the situation to show the evidence of cloning...otherwise your and his words or statements have no weight because this is only empty talking. I´m sorry but i don´t understand why you just can´t show the proof, what´s so hard about that? Then every discussion would disappear and everything would be clear.

Mig's picture


I could not have said it better myself.

@Felix Kling
I really find the "I am no programmer" comments amusing , If your not qualified to comment, then don't

brabo's picture

Come on guys. The only way to proof that something is a clone, is to make your own source code open so both codes can be put next to each other and the copied parts can be shown. However opening your own source code means commercially suicide because from then onwards anybody can copy the code very easy. The Rybka team is living from commercialising their product. What you ask is that they give up their own salary just to proof that they are right about the cloning. So showing evidence means an absolute income loss. Not giving evidence probably also means some loss because some people will believe the other party but I expect less revenue loss.
In the end if it concerns here pirats with clones then they achieved in any way their goal by destabillizing the commercial market.

Felix Kling's picture

@KingTal (and others): So why did in history of chess engines noone before use fake names besides cloners? Just coincidence? Normally a programmer is quite proud of his work, since writing such a program from scratch is a major achievement. Those reasons you give, like "humour" and so on, are so unlikely.

@Arne: Vas stated that he had a good look at Fruit (like any programmer), but that's a big difference to a clone, since a clone is using another engine as basis and not just taking some ideas and so on.
About Vas lying: Vas never accused engines like Stockfish etc. of being clones, even if they are strong and free etc. . When he said the clone thing about Strelka, the "author" himself admitted it later on. Vas is a honest person.
When you saw how paranoid Vas is with his beta versions (in Manz he used an expensive encrypted USB stick for the latest Rybka) you know that the danger of decompiling Rybka is real.
The current Rybka betas are a major improvement anyway, so Rybka's position was never in danger.

Btw., other teams like the Hiarcs team deal the same way with those clones, they are banned from the major rating lists where experts decide what to test (they don't test clones) and so on. I think at some point believing that all this is a conspiracy, that everything said by the experts is wrong and all this is just done because of Vas being afraid is ridiculous.

Arne Moll's picture

@Felix: As far as I'm concerned, the discussion is not about Rybka. It's not about Vas's honesty, which I don't doubt. It's about IPPOLIT/Firebird. Their programmers are accused of piracy, theft and cloning. The engines are banned from various competitions. On some sites, their software can't even be mentioned. These are serious allegations, but what's lacking is evidence to substantiate these accusations. This is the heart of the matter. Serious claims should be backed with serious evidence, not with suspicions or arguments that their behaviour is not like that of other programmers. Is there or is there not a serious case against them? That is the question, and that is how we decide whether using Firebird or similar engines is morally acceptable.

David Miralles's picture

@Brabo: I guess a judge could be the ideal person to whom you could show the evidences without commercial risk

djbl's picture

good to see that rajilich is still using felix king as his mouth piece. tell me, when will he get his voice back??

Felix Kling's picture

Arne, the only one who can tell you if it's a clone or not is Vas. If he says so, this should be taken as fact. The whole picture together with what Vas says just leaves one reasonable conclusion: it's a clone.

brabo's picture

Some problems pop up if you go to court. Who will you sue to get compensation from because the authors of e.g. Firebird are unknown.
The judge will need assistance to understand how programming is done which leads again to extra risks of keeping the source code closed.
Which judge in which country is valid to give a verdict and can force a penalty to one party.
Finally who will pay for the whole trial except the Rybka-team and even if they win, is it worth the money invested?

Until now I've not seen any proof of credibility of the Firebird team. On the other hand the Rybka-team has earned its stripes over the last couple of years. For me it is not difficult to choose side between somebody hiding himself and somebody reasonable open to everybody.

To me the discussion is more about if chessengines can/ should be protected as an intellectual property. In the 80s Robert Huebner already claimed that the notation sheet should be the intellectuel property of the players. He lost his case so logically some people think the same about chessengines. I think this is wrong.

Ippolit Supporter's picture

@Felix Kling

"I’m no programmer, but it’s obvious that those are no original engines when you use your brain."

Right.. And your "non-programmer" brain cannot comprehend the logic of using an alias?

After reading your lengthy nonsense replies, it is so obvious that you are only selecting the comments that you make a counter argument. But after reading all 6 of your comments above, I can only see your "fake name" argument which is totally irrelevant to the chess engines. You cannot address the biggest issue here, which is about showing evidence. Why? Because YOU CANNOT, and NEITHER CAN VAS.

If you, Vas, and the entire "Rybka Religion" are really the "good guys" here, then why is it so difficult for you to prove that? I am pretty sure you are not enjoying this debate that you obviously cannot win, so why don't you just end all these once and for all?

Oh yeah, I completely agree with post above that your comments here are weightless without proof. :)

I have no personal issues against you. I completely understand why you are like that (because you are making money from Rybka). So if I am in a similar position, I'll probably do the exact same thing that you're doing. And I understand the reason why you cannot give us useful information here. Because you don't have any, Vas did not show you any proof too (because he doesn't have any), and all you have is his "honest" words.


Ippolit Supporter's picture

"the only one who can tell you if it’s a clone or not is Vas. If he says so, this should be taken as fact. The whole picture together with what Vas says just leaves one reasonable conclusion: it’s a clone."

Wow.. I am truly convinced. :)


David Miralles's picture

@brabo: Yes, you are right, it is not as easy as I've put it, and to be honest I'm far from being an expert in law, but I'm not sure these problems are the real reason for Rybka not to go to court.
The authors of Firebird are not completely unknown, or at least not that difficult to find. Yes, there is a trial cost but if you win your commercial interests will be protected. It is not worth? well, I don't know ... and I don't think the jurisdiction issue is a real problem.

Another reason for not going to court could be that they could have no evidences that it is a clone, or that they cloned Fruit in the same measure that Firebird cloned Rybka, and they should refute this in order to win the case.

Even though I share your arguments about credibility and about intellectual property I definitely that the court is the only place where Rybka could totally protect its interests.

brabo's picture

@David: I think we more or less agree.
So now it is up to every individual chessplayer to decide if he downloads and uses Firebird or not. If you do then you, or believe the credibility of the Firebird team more than the credibility of the Rybka-team (which is besides some exceptions not the case) or you simply don't think high about intellectual property rights when you can take advantage of something (which I believe is likely almost everbody who downloads the program).

I've seen even grandmasters downloading Firebird. Well next time if a book is published by them then I hope that they also don't cry about illegal copies and breaking of intellectual property rights.

test's picture

Vasik Rajlich can't legally stop the spreading of these programs he don't like unless he has a court order. It's possible to take this to court. Example: Apple sues anonymous people over leak of unreleased Apple product info on Web, though all that hassle is probably not worth it.

The Computer-Chess Wiki has this to say about Ippolit: C source; Win32/64 Linux 32; mp; accused of being a clone but no tangible proof has been offered; There are many forks of the Ippolit codebase; other forks: RobboLito, Igorrit, IvanHoe, FireBird; Latest release: FireBird 1.2

(See Chess Engine List & Clone Engine List)

Of course this is no definite objective proof of anything and we have kind of a reverse situation where it is the accuser who refuses to let anyone look at his source for comparison.

In the FAQ they have an item about clones: ... In particular over the years, more than one engine has being forced out of official tournaments, either because it is proven to be a clone, or on suspicions of being one and refusal to show the source. ... Still you can't ever be sure unless you look at the source. This has obvious problems because the author of the engine might prefer not to let anyone, no matter how trusted, look into his code for fear of losing trade secrets. Would the author of Rybka, Fritz, or Shredder really allow someone, no matter how respected, to look at their source?

Arne Moll's picture


"If he says so, this should be taken as fact."

In Holland we say: "that's like the butcher judging his own meat". It means that an interested party is simply not a reliable source of information, even if he happens to be right. This is a basic fact of law, rhetorics and science. That's why we have independant judges, evidence-based trials, peer-review, etc.

The fact that this, well, 'dogma' is the sole basis of a serious accusation is really quite amazing in my opinion, but apparently it's as far as the Rybka team wants to take this. And I guess we should respect that decision as well, even if I personally find it very puzzling.

Steven Simons's picture


You Said :

“the only one who can tell you if it’s a clone or not is Vas. If he says so, this should be taken as fact. The whole picture together with what Vas says just leaves one reasonable conclusion: it’s a clone.”

I say:

LOL you didn't just say that, please tell me you didn't!! , what incredible skills of deduction you have..

Here is an analogy for you if the "Butcher analogy above by Arne wasn't clear enough for you.

Did you know that "I" make the best apple pie in the world ? Oh no hang on, ill have to wait for the panel of applepie judges to decide.

Now you see, you have to bring ApplePie(tm) judges to decide whether or not ippolit family are clones or not, and using that SAME measuring stick decide if Rybka is indeed a clone or not.

You see.. very simple.. Let the applepie judges do the judging and not the fruitgate insider..

You Felix can't do bad to the hand that feeds you, we get that.

rupelstiltskin's picture


You clearly have a conflict of interest on this subject, and there is no reason I should take anything Vas has to say as fact. My reason for not trusting his word is because he has never released the Rybka 3 bug fixes that he promised. I remember he gave his word on that as well.

So why should we trust him exactly?

alpha123's picture

Felix Kling:
"@alpha123. Easy. They added quite some stuff to try to obfuscate the cloning, some tables Larry added to Rybka are slightly modified and such things, some algorithms are added, some are removed. It’s actually easy to create an engine with totally different output. About the big effort: Well, it’s not the first time. See Strelka. About the UCI parser: I’m no programmer, there may be classical examples or not many alternatives for that. However, such things can hardly be considered real inventions of a program. About the evaluation tables: I don’t know any details about it. But I don’t see why I should trust Mr. Hyatt more than Vas. Afaik Fabien never did such accusations and everything seems fine for him, so even if programmers took stuff from Fruit (and it’s clear that all major programmers had a good look at it) I don’t see a reason to consider any modern engine a fruit clone. again, I don’t know the Rybka sources and the only one who could answer that question is Vas."

"It’s actually easy to create an engine with totally different output."

It's ironic that that argument works well with Fruit/Rybka..... the obfuscated node count and depth.....

"About the big effort: Well, it’s not the first time. See Strelka."

Which was exactly the same strength as Rybka..... and had the same output..... that's how we figured out it was a clone, remember?

"About the UCI parser: I’m no programmer, there may be classical examples or not many alternatives for that."

Um, well, the obvious alternative is to not make it inline. Fruit, as far as I can tell, was the only one to do use it inline.

"However, such things can hardly be considered real inventions of a program."

Agreed, but it was kinda a unique fruity thing.

"But I don’t see why I should trust Mr. Hyatt more than Vas."

The father of modern computer chess vs. the father of modern suspicious chess engine activities.

"I don’t see a reason to consider any modern engine a fruit clone."

Except that a certain modern engine may have Fruit code in it. That would qualify it as a clone, I think.

"again, I don’t know the Rybka sources and the only one who could answer that question is Vas."

So why are you answering it????

Estragon's picture

I understand the inherent "Catch-22" involved in proving theft of "secret code," that one must expose the secret to prove the theft. In a lawsuit, a court might appoint a Special Master to review such things privately and report his findings to the court. However, it is difficult to file a lawsuit against anonymous persons, and even more difficult to recover damages when they are giving the product away for free.

Still, the burden of proof always lies with the one making the assertion. Saying, "Take my word as fact" just doesn't convince anyone.


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