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

Fire Bird far from best of IPPOLIT engines
try this from Angels77
vlado compile plus source file

El Guest's picture

find more on her forum

inc peter pans latest compile ...the strongest chess engine in the world !!!!

El Guest's picture

ps naum 4.2 crushes deep rykba3 into 4th place of top chess engines :)

El Guest'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.”

vlas may be your god , he may even be you , but his word is not sacred and your a muppet if believe only vas can tell if these engines are as you ignorently call "clone"
i suggest you google the word clone and perhaps libel :)

BTO7's picture

Well what do we really know at this point ? Vas has pointed a finger with no proof. Vas lets face it has gotten lazy and is letting down his user base. He has not come out with his Rybka 3+ for those who have bought 3 from him (like he said he would)....he has not release Rybka 4 ...and blows everyone off at his forum with vague TBD. Its over a year and a half since he has released anything at all. Seems to me hes too busy with cluster building and is just gonna try to beat other programmers through online machinery.....really more then anything. What should Vas think ? ....everyone is just gonna sit around waiting and waiting? Seems this Ipploit team is busy ...getting us chess fans what we want ...STRONGER ENGINES in a TIMELY fashion. Its been so long since the release of Rybka 3 its nearly a dinosaur and others are catching up bottom line. Just as the Naum auther noted ...he sees other chess engines catching up so hes back to work .....seems Vas as i said has gotten lazy and is just letting his fans down with SLOW work......If its taking Vas a year and a half to come up with something while others are producing new better ....with less bug engines every month or two ....then what has Vas been doing ???? Too worried about cluster and not getting busy taking care of his clients. Rybka 3 has tons of bugs and it just seems he dont really want to spend the time ( again lazy route) to get them their fixes.....then its no wonder this is all happening to him. Less worry about clusters and getting back down to business of getting his customers something new in a timely fashion seems would be in his best interest. Im sure hes honest but ....did he say Rybka 3 owners would get a update ? Has he honored this? Its like take the money and run. Rybka customers are fed up with his delays and lack of updates not to mention not even getting Rybka 4 out after over a year and half of waiting. If others are getting out engines (that are suppose to be clones) every month ...then whats Vas excuse for it being a year and a half. Simple his focus is not on his customers ...its his pet project of this online engine that most could care a less about and in the mean time other programs have caught up and giving chess fans what they really want stronger engines they can use at home. It just doesnt seem hes too worried about getting his customers their new engine this rate ...Rybka 5 will take at least 3 years from the release of 4 ...if ever it comes out......hes just too slow imho. As far as Ipploit family being clones ? I say either PUT UP OR SHUT UP . No disrespect meant in anything i have said here ...just my opinion ...take care chess fans :)

ask's picture

when ippolit should be a clone, then how many percent of rybka are in ippolit? 5 or 10 % ?

how look the analysis output of this position:

1.e4 c5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 e5 5.Bxc6 dxc6 6.Nxe5

of fruit, different rybka versions, strelka and ippos ?

orange.engine's picture

Arne Moll: of course, sleeping is a must. Thankyou for you response and I apologize for being impatient.

For providing proves about cloning it's not necesarry to show to everybody the complete original engine's code. In the Strelka issue, proves were provided by Rybka Team.

El Guest's picture

the rykba team prove nothing they shout loudest in the past now they rely on a few to shout for them
the shouts are drownded out by weep rykbas failures and vas's silence with the tide of non clone engines a super car a clone of a model ford t ?
pick your own analogy if that does not suit you ,,are you a clone of your ancestors because you have a portion of there d.n.a or "compile"
grow up admit the truth , better programers made better engines

Ippolit Supporter's picture

I guess Mr. Felix Kling stopped replying because he has nothing more intelligent to say. So lets allow the poor guy weep to his God Vas. :D

Arne Moll's picture

@El guest, Ipplolit supporter & some others:

Some of your arguments are interesting but please keep the discussion objective. I don't mind strong opinions but personal attacks on users of this website only make real arguments look weaker so drop them already. Let's set an example that a polite and correct discussion on such a controversial subject is still possible on the internet. Thanks.

El Guest's picture

ive delivered no "personal comments" that could be concievably fairly interprated as " personal attacks"
i tire of an almost religiose "Blind Faith " arguments when the likes of mr king avoid answereing honestly
they attempt to defend the indefensible and trot out the same tired old platitudes that insult the inteligence of the average moron
but i shall respect your words and we thank you for allowing freedom of speech here :)

Chaos & Anarchy Freedom's picture

Hi guys !

I don't like Rybka !
I don't like Ippo-Robbo-Igorr-Fire-Ivan family !
Why ?
Because they are in a new class of chess engines :
A minimalistic evaluation , a savage pruning.................all for speed !
I have an impressive chess games collection between the speed chess engines and old , but well ballanced chess engines.Ok , these engines won the matches , but lost also a lot of games despite the great depth and the great KN/s.
Tomorrow , on immortal chess site will be posted some samples.
For analysing my games I use only Hiarcs , Shredder , Gandalf............they are very good & well ballanced chess engines.
Only for fun !

Chaos&Anarchy Freedom

PS: Felix Kling ? Just an youth..............................................................

Yo's picture

Ippolit sources were available in internet *before* May 2009. Only the word was spreaded in October 2009. Meanwhile there was lot of time to work on DERIVATIVES, as initial sources (clearly got by a dissasembler program, in opinionn on many from Rybka) were buggy and simply didn't work.

test's picture

Some say it's possible to successfully disassemble such complex program like Rybka, others say it's not. I can speculate that it's at least extremely difficult and not really worth it as you can't commercialize or play tournaments with a clone without having to prove it's not a clone.

On the chess wiki clone list there are mainly open source programs, but there are also some closed source programs. I assume they know what they are talking about so until somebody convinces me I shouldn't I will accept that it's possible to clone a closed source program. The existence of clones also means that it's easy to falsely accuse, hence without more definite proof I'm on the fence.

dollyman's picture

hi everybody!
just say : rybka is half dead !
Rajlich don't support it until now, and rybka still be beaten by ipoolit family, that's why i think we will never hear about rybka very soon,
There are so many difference between the 2 engines, size for example, style of play!
Just admit rybka is over if clone or not, if rajlich is wise, just show us the new rybka

BTO7's picture

@felix kling you just said up above and i quote "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. " Well if it so easy ..whats Vas excuse for not getting Rybka 3 buyers their update and bug fixes ? If its so easy to make his product better through all these tweaks ...WHY were they NOT done long ago for his customers of Rybka 3? If its so easy ...why is it been a year and half and NO Rybka 4? If its so easy he should be on Rybka 6 by now? If it's so easy why has he done nothing now for so long and is leaving his clients on the fence waiting for their updates that YOU have just claimed are so EASY to do? I dont follow your logic here felix. So EASY yet Vas has produced nothing for a year and half? Felix Vas has gotten too comfortable.....he got paid commercial price for his product and is getting his customers their fixes like its ONLY a HOBBY for him. Like he only gets around to it in his spare time ? Nobody should know his program better then him ....even if hes right that some others are a clone of his.....yet they can FIX all the bugs and increase the strength REGULARLY and he cant get some simple FIXES to his clients of Rybka 3 ? Hes complaining about clones on one hand and STICKING it to his customers on the other hand with no updates ? Hardly the way to keep people happy . IF it so EASY felix as you have said :)

rupelstiltskin's picture


Very well said ...., I agree with everything you stated above!

El Guest's picture

from Sandi
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Default Re: IvanHoe

Generally were made significant progress in all areas.
As single engine is IvanHoe at least as strong as Robbolito.
In the area dual core,the few tests were also more positive than with the
older sources.
The largest increase was achieved with the most compiles for 4 cores.
More than 80% of Peterpan's POPCNT for i7 and i5 systems destroy Rybka.
One can determine statistically that the average rate against the strongest
opponent is 65-75%!!
On 4 threads IvanHoe pulverized the whole world.
Much better is also the difficult scaling to 8 threads.
Peterpan and Tester have 6 compiles with distinct and constant results against the little fish.
Pity the JR not worked in last time.We should thank him too.
It would be good if the new source IvanHoe 62 improved a little more agressivity.Thus,the draw ratio would fall and the results even more clearly
in all sectors!!

Cortex's picture

Remember Assassin's Creed 2? I'm definitely not a fan of remote computiong, especially when your net connection is sluggish...

IanO's picture

@IanO: I was able to compile Igorrit fine on Mac OS X (after setting correct tool locations in the Makefile to /usr/bin and setting default CPUS_SIZE to 2). So there is indeed a multicore option for the Mac!

Super Duper's picture

I guess you will always have people that don't mind using stolen goods they haven't paid for just like you might someone that finds nothing wrong with buying a stolen Iphone at half price. He can argue that there is no 100% proof that it is stolen since he didn't see the theft, and even if it was then it is not his problem since he did not do the physical act of stealing. It is interesting to see that some are fighting hard to make the Ippolit engines get legitimacy as an original engine, but that ain't gonna happen. There is a very good reason why the authors are anonymous as if the names come out, there will be some names that would indeed be very surprising. Anyone who says that Ippolit is not based on decompiled R3 code is either lying, playing dumb or simply clueless about chess engines.

The Riddler's picture

Well Super Duper, let us say that you decided to buy an "phone 4" and for this, you also decided to sell your "phone 3", that you bought legally. Suddenly you realized that no one is gonna buy you "phone 3" unless you sell it half price.

Now some one banned you as as a phone theft and dont let you sell your "phone 3" because there is no 100% proof that you bought it. They SAY that you ticket is false because they SAY they are compare it with their records)

Are you a theft only because you sell your Iphone 3 half price? Are you a theft because they SAY your ticket is false?
I think that you must read your constitution right now.

alpha123's picture

I am waiting for the return of Kling..... sad that he will not defend Vas in his time of need.....

El Guest's picture

he prays to his false idol Vas or perhaps to St Jude ..patron Saint of Lost causes


val's picture

A bit of nit-picking. It should be `Vorobyaninov`, not `Vorobyanov`.

test's picture

@Super Duper

I agree with you on the ethical issue except to say that it is not necessarilly always so simple as you make it out to be. (See my 1st post above.)

About Ippolit you don't really give any arguments to support your position, but then again without solid proof this whole discussion is based on hearsay or speculation anyway.

"There is a very good reason why the authors are anonymous as if the names come out, there will be some names that would indeed be very surprising."

You sound as if you know the names. If you know the names then give them, if you don't know the names then how can you be so sure?

BTO7's picture

Gotta love the shoot from the hip statements of SuperDave with out a shred of evidence to back his claim and in the mean time Vas has customers with a buggy R3 that have never gotten their fixes. Seems to me ...regardless of the situation Vas has customers paying the price due to his slow work and LACK of attention of his original project R3 favor of project building. Bottom line he figured he was so far ahead of everyone ...he just laid back and blew off ever getting a R3+ out and now all he can do is point fingers at every engine that comes out as strong as his. There is a song for this ..... a little less TALK and a lot more ACTION is whats needed in the Rybka camp.

alpha123's picture

Super Duper: "Anyone who says that Ippolit is not based on decompiled R3 code is either lying, playing dumb or simply clueless about chess engines."

Alright, tell me why you think it is based on decompiled R3.

BTW, Anyone who says that Ippolit is a modified decompiled R3 is either lying, playing dumb, or simply clueless about decompiling and disassembling and/or computer chess in general.

El Guest's picture

only a muppet or vas sycophant would liken buying stolen i phone to the debate over the strongest chess engine (IvanHoev63 ) in the world being a rykba 3 clone
do any of these fools understand the meaning of "clone" identical being / product
i ask again is felix king a clone of vas or anyone , one sper + one egg = life and a basis for growth just as fruits code spawned rykba
ivanhoe is about as similar to rykba as felix's old engine is to , he is not a clone of his g g grand parent but has a little of there genes within him

get it now Super Pooper ?

kuku's picture

can anyone give a link to the Fire homepage, or at least a link to the page with the latest version?


toto4music's picture

Hello everybody,

The think appears clear is that rybka never has time to born, because better engine had exist (like robbolito, and now fire) while rybka was released.
So to conclude, no one is forced to buy chess engine, just progress with those that exist and are free ; stockfish, robbolito and fire.

Great job to fire's team.

support socks's picture

Ok, what is the deal with so many comments being completely off topic? Is this an ADHD Forum?


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