Legal status of Eman?

[Ovyron]

I find really weird that I haven't seen much talk about the engine Eman.

It is a Stockfish derivative, and I have to say it's the most impressive derivative I've evers seen. Perhaps, it is the strongest engine that has been installed on my hardware, ever, and by a lot. This thing is FAST, and I have never seen anything with this speed.

But what do I mean by "fast"? Well, let's define speed as the amount of time it takes the engine to find "decent move", and play it on the board. And let's define "decent move", as one that doesn't lose on the spot, so basically, all moves are decent unless they're game losing blunders. Decent moves can be bested with more depth, or they may not cause as much trouble to the opponent as possible, so they may not be best, or optimal, but the point is, if you only play decent moves in a game on a given time control, you're undefeatable, by definition (conversely, all decided games had a move that wasn't decent, played by someone.)

I've been using Eman on InfinityChess under the handle Vytron, and I haven't had problems drawing games against much stronger hardware. Because their GUI is unstable, I've been having to use only 3CPU of my ancient Q8200 @2.33Ghz, averaging some 1700kn/s, against the likes of people ranging from 6000kn/s to monstruous 28000kn/s on 16CPU core machines. I've been outright outsearched, by the likes of playing Depth 20 moves against Depth 34 moves and such.

And it doesn't matter, that's enough for my Eman to find the decent moves needed and make them unable to defeat me! I've had this account for over 7 years, back then I used the strongest Stockfishes of the era, and remained a game loser with 2050 rating. With Eman, against 2500 rated players in much stronger hardware, running the latest versions of ASMFish, Stockfish, Brainfish and Komodo, I have no problem drawing. (not that I'm undefeatable or undefeated, but there's openings I can play for that, so it seems when they do it is because I come up with a bad position out of book)

I'm glad I never invested in stronger hardware if these guys can't defeat me with it XD

I just wanted to put Eman into context, because what insterests me is its legal status. Eman is a private engine, and the only way to get it is to get in direct contact with the developer and get a private link. You're requested to not share the link.

When you get the link, there's no source code to be found.

My inquiries are about if this complies with Stockfish's licence (as there's technically no distribution). And if not, if this has anything to do with the deafening silence about Eman.

If my assumptions are correct, in my honest opinion, there's a world out there where Eman's developer did his changes to Stockfish's code and kept it for personal use to himself, and our current world where he shared his work as closed source for the people that know to enjoy. And after what I've said on this thread, I'm clearly much happier in our current world.

[zullil]

Find the statement copied below at https://stockfishchess.org/about/

About the GPL

Stockfish is free, and distributed under the GNU General Public License Version 3 (GPLv3). Essentially, this means that you are free to do almost exactly what you want with the program, including distributing it among your friends, making it available for download from your web site, selling it (either by itself or as part of some bigger software package), or using it as the starting point for a software project of your own.

The only real limitation is that whenever you distribute Stockfish in some way, you must always include the full source code, or a pointer to where the source code can be found. If you make any changes to the source code, these changes must also be made available under the GPL.

[hgm]

Giving a modified executable to anyone without the source code is a GPL violation. But like with most breaches of the law, if no one presses charges, this has no consequences. Anyone getting the executable this way can demand the source code, (no matter what they made you promise in order to get the executable, because asking such promisies is a GPL violation in the first place, making them void) and the GPL violation would be manifest if that request is refused.

[supersharp77]

I find really weird that I haven't seen much talk about the engine Eman.

It is a Stockfish derivative, and I have to say it's the most impressive derivative I've evers seen. Perhaps, it is the strongest engine that has been installed on my hardware, ever, and by a lot. This thing is FAST, and I have never seen anything with this speed.

But what do I mean by "fast"? Well, let's define speed as the amount of time it takes the engine to find "decent move", and play it on the board. And let's define "decent move", as one that doesn't lose on the spot, so basically, all moves are decent unless they're game losing blunders. Decent moves can be bested with more depth, or they may not cause as much trouble to the opponent as possible, so they may not be best, or optimal, but the point is, if you only play decent moves in a game on a given time control, you're undefeatable, by definition (conversely, all decided games had a move that wasn't decent, played by someone.)

I've been using Eman on InfinityChess under the handle Vytron, and I haven't had problems drawing games against much stronger hardware. Because their GUI is unstable, I've been having to use only 3CPU of my ancient Q8200 @2.33Ghz, averaging some 1700kn/s, against the likes of people ranging from 6000kn/s to monstruous 28000kn/s on 16CPU core machines. I've been outright outsearched, by the likes of playing Depth 20 moves against Depth 34 moves and such.

And it doesn't matter, that's enough for my Eman to find the decent moves needed and make them unable to defeat me! I've had this account for over 7 years, back then I used the strongest Stockfishes of the era, and remained a game loser with 2050 rating. With Eman, against 2500 rated players in much stronger hardware, running the latest versions of ASMFish, Stockfish, Brainfish and Komodo, I have no problem drawing. (not that I'm undefeatable or undefeated, but there's openings I can play for that, so it seems when they do it is because I come up with a bad position out of book)

I'm glad I never invested in stronger hardware if these guys can't defeat me with it XD

I just wanted to put Eman into context..

Eman is a very stong engine no doubt and Have been testing it for around 8 months or so and it has very few losses..quite strong indeed..3.40 3.01 and 3.02 are still active in my KO tourney. I believe the engine author has also tweaked a few other Stockfish clones (None of whom have src codes attached) Reminds me of Raubfisch and Betafish some of MZ's private compiles not easy to obtain, no src and Stronger than Stockfish original by a bit..

[Eelco de Groot]

An easy way to bring down the losses would be to include an opening book. You'd just copy Brainfish and maybe hide the the immediate moves. I don't want to investigate, this thing may not have a book at all but some others other do I believe? I understand people want to hobby and extensively document their books like Ed does with Pro Deo but it is also bit annoying to me when people include opening books in Stockfish and the Stockfish with book is then tested for instance in a tournament by people who don't realize this, the clone is declared the 'new strongest engine on earth' and it is not even corrected on this forum by anyone anymore.

[corres]

An easy way to bring down the losses would be to include an opening book. You'd just copy Brainfish and maybe hide the the immediate moves. I don't want to investigate, this thing may not have a book at all but some others other do I believe? I understand people want to hobby and extensively document their books like Ed does with Pro Deo but it is also bit annoying to me when people include opening books in Stockfish and the Stockfish with book is then tested for instance in a tournament by people who don't realize this, the clone is declared the 'new strongest engine on earth' and it is not even corrected on this forum by anyone anymore.

It is not an accident that in the engine-engine competition it is forbidden to enter an engine with "built-in"
opening book.
But who can control this rule during an online competition?
Nobody.

[crem]

GPL allows anyone to make modifications without releasing source code.
What GPL doesn't allow is distributing (in GPLv3 terms, "conveying") binary without making source available.

Distribution is not only putting it into publicly available place, but also e.g. sending physical disks by mail by requests.
This is pretty similar to what Eman author does.

There is an exception about private software. If you make a modifications for a particular user (or company) and don't release to public, you are free to do that without having to share either binary or sources with the world.

With Eman it's clearly not the case, it is not software made specifially for a particular user or company.

Here is excerpt from GPL FAQ:

Q: Is making and using multiple copies within one organization or company “distribution”?

A: No, in that case the organization is just making the copies for itself. As a consequence, a company or other organization can develop a modified version and install that version through its own facilities, without giving the staff permission to release that modified version to outsiders.

However, when the organization transfers copies to other organizations or individuals, that is distribution. In particular, providing copies to contractors for use off-site is distribution.

One popular confirmed type of GPL violation is having "closed betas" of GPL software (some Linux distributions do that). For me Eman looks very similar.

[hgm]

There is an exception about private software. If you make a modifications for a particular user (or company) and don't release to public, you are free to do that without having to share either binary or sources with the world.

I think there never is an obligation to share source with the world. Just with the people you gave the binary (if they want it). If I share my modified binary with a group of persons, persons outside the group do not derive any rights from that. (If only because such rights would be completely unenforcible, as no one outside the group would be able to prove what we shared, or indeed whether we shared anything.)

[chrisw]

GPL allows anyone to make modifications without releasing source code.
What GPL doesn't allow is distributing (in GPLv3 terms, "conveying") binary without making source available.

Distribution is not only putting it into publicly available place, but also e.g. sending physical disks by mail by requests.
This is pretty similar to what Eman author does.

There is an exception about private software. If you make a modifications for a particular user (or company) and don't release to public, you are free to do that without having to share either binary or sources with the world.

With Eman it's clearly not the case, it is not software made specifially for a particular user or company.

Here is excerpt from GPL FAQ:

Q: Is making and using multiple copies within one organization or company “distribution”?

A: No, in that case the organization is just making the copies for itself. As a consequence, a company or other organization can develop a modified version and install that version through its own facilities, without giving the staff permission to release that modified version to outsiders.

However, when the organization transfers copies to other organizations or individuals, that is distribution.

It would be bizarre if "use by staff" for testing purposes (a) above, would not extend to "contracted off site testers"

In particular, providing copies to contractors for use off-site is distribution.

key would be if the organisation/individual solicited testers and contracted them with necessary restrictions, or whether Joe Public can just apply to be a tester and receive a copy. Testers would have to actually be intended to test, and not act as PR, which is mostly their role at present.

One popular confirmed type of GPL violation is having "closed betas" of GPL software (some Linux distributions do that). For me Eman looks very similar.

[smatovic]

Despite all the paragraph riding, it is simply against the GPL philosophy.

The deal is that you can use it, but all the nice improvements have to come back,
to be open and useful to everyone.

If you don't like the deal, then use some other code base, MIT, BSD etc..

--
Srdja