Finding clones...

[chrisw]

So in my opinion:
- Rybka 1.0 is not a clone of Fruit 2.1, it is somehow different and better
- Rybka 1.0 started as the source code of Fruit 2.1

We have a different opinion what clone means. Starting with the source code would violate the GPL even if every single line is changed. So I would call this cloneing.

But as I stated several times before, it must not be illegal in case the original author agrees.

Alex

Then, what is the purpose of "open source" chess programs at all?
So you can study other's program, but be careful not to study it very well!
Because if you remember too much of it then there's a possibility that you will unintentionally repeat
the program's structure, or parts of code when writing your own program!

You can read other programmer's code just to learn what you must not done in your own...

So open source programs are a good way to "copyright" code and ideas?

If Fruit had not been released as open source then we would never have
seen such degenerated debates about cloning here, and stupid and childish
"psychological" dissertations about envy - not envy in a forum about Computer Chess.

The purpose of open source as defended by the GPL is to allow code to be used and re-used and stay "open" without allowing somebody to "close" it again.

Hence the "if you start from GPL code, the result is still GPL".

The purpose of GPL'ed chess programs is to allow people to use and re-use the chess code without allowing somebody to modifiy it and then hide it.

Hence, if you want to write a commercial chess program you must NOT start from an open source one, because by starting from an open source program you explicitely deny yourself the right to hide the source if you publish your program.



// Christophe

Not so. If you start from GPL and change everything then the GPL licence no longer applies. So you can use the GPL source as testbed, slowly change it and ensure the changes work, and then, in the end, with everything changed, the GPL licence is no longer applicable - it's now your code. Clause 0 - GPL licence.

[Dr.Wael Deeb]

No you don't get the idea.
The idea is that you can study the program as well as you want, you can use all the ideas as also all the code you want from the open source program, you can write everything you want containing anything you want from the open source!
There is no copyright of ideas or code. There is no restriction! .....Well there is only one. The simplest:
You should publish the source code of the final program!


So you can do everything you want with the code and the ideas of open source programs under GNU GPL as long as you publish the source code.

No, George. I got the idea very well. I know what GPL is. Just tried to explain why I dislike it.
Of course, it can be very appropriate in other areas of programming when many programmers contribute to develop some useful utility.
But computer chess is mostly about lonely programmers, and releasing code under GPL does not make much sense. At least in my opinion...

Correct,because of the competitve soul of the field....

[Graham Banks]

releasing code under GPL does not make much sense. At least in my opinion...

Freedom of choice and some obviously feel it worthwhile to do so.

[Alexander Schmidt]

$2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:

There is no word about modify the whole program. If you change a part, everything is GPL, and not only the original parts. Then, if you change the next part, everything is GPL.

I am no expert, but an GPL expert (I think it was Daniel Mehrmann) told me it would still be GPL. But I am not sure about which version we talked.

[tiger]

So in my opinion:
- Rybka 1.0 is not a clone of Fruit 2.1, it is somehow different and better
- Rybka 1.0 started as the source code of Fruit 2.1

We have a different opinion what clone means. Starting with the source code would violate the GPL even if every single line is changed. So I would call this cloneing.

But as I stated several times before, it must not be illegal in case the original author agrees.

Alex

Then, what is the purpose of "open source" chess programs at all?
So you can study other's program, but be careful not to study it very well!
Because if you remember too much of it then there's a possibility that you will unintentionally repeat
the program's structure, or parts of code when writing your own program!

You can read other programmer's code just to learn what you must not done in your own...

So open source programs are a good way to "copyright" code and ideas?

If Fruit had not been released as open source then we would never have
seen such degenerated debates about cloning here, and stupid and childish
"psychological" dissertations about envy - not envy in a forum about Computer Chess.

The purpose of open source as defended by the GPL is to allow code to be used and re-used and stay "open" without allowing somebody to "close" it again.

Hence the "if you start from GPL code, the result is still GPL".

The purpose of GPL'ed chess programs is to allow people to use and re-use the chess code without allowing somebody to modifiy it and then hide it.

Hence, if you want to write a commercial chess program you must NOT start from an open source one, because by starting from an open source program you explicitely deny yourself the right to hide the source if you publish your program.



// Christophe

Not so. If you start from GPL and change everything then the GPL licence no longer applies. So you can use the GPL source as testbed, slowly change it and ensure the changes work, and then, in the end, with everything changed, the GPL licence is no longer applicable - it's now your code. Clause 0 - GPL licence.

I'm not even sure about this, as every iteration in the modifying process is still governed by the GPL licence. So when you change the "last" line and you make iteration N totally different from iteration 0, you are not done. Because there is only a single line changed in iteration N from iteration N-1, and N-1 was still covered by the GPL.

Anyway, the convoluted process you describe and that would supposedly allow to transform GPL code into non-GPL code is very borderline and in my opinion clearly against the spirit of the GPL.

The GPL says that if you do not want to end with GPL'ed code, then just don't start from GPL'ed code.

So instead of changing any line of code in order to acrobatically escape the GPL liability, what about writing everything yourself from scratch?

Now this discussion is maybe not even relevant, as it may simply be that we find GPL'ed code inside the program in question, which makes the whole code GPL.

Here is the relevant part of the GPL licence:

These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.

// Christophe

[chrisw]

$2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:

There is no word about modify the whole program. If you change a part, everything is GPL, and not only the original parts. Then, if you change the next part, everything is GPL.

I am no expert, but an GPL expert (I think it was Daniel Mehrmann) told me it would still be GPL. But I am not sure about which version we talked.

Read Clause 0.

If you modify the program it is still GPL, sure, but if you modify it completely such that no original code chunks remain then the GPL licence no longer applies. All stated clearly in Clause 0. No other clauses have any validity at the point the last code chunk is rewritten.

[Alexander Schmidt]

Moderation tools has this split function - If you remove the original post which is offensive, then subsequent replies to it will be gone as well. Really poor mod tools I think.

Think about not to delete things like:

"It is not as clear as you want to make us believe"

Is this offending?? Oh, then I must apologize... I meant it like I wrote it, not offending at all..

[rhollay]

No you don't get the idea.
The idea is that you can study the program as well as you want, you can use all the ideas as also all the code you want from the open source program, you can write everything you want containing anything you want from the open source!
There is no copyright of ideas or code. There is no restriction! .....Well there is only one. The simplest:
You should publish the source code of the final program!


So you can do everything you want with the code and the ideas of open source programs under GNU GPL as long as you publish the source code.

No, George. I got the idea very well. I know what GPL is. Just tried to explain why I dislike it.
Of course, it can be very appropriate in other areas of programming when many programmers contribute to develop some useful utility.
But computer chess is mostly about lonely programmers, and releasing code under GPL does not make much sense. At least in my opinion...

Correct,because of the competitve soul of the field....

Absolutely!

[Alexander Schmidt]

Clause 0 - GPL licence.

Misinterpretation, re-read it:

"means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications "

and watch for the addition "or modifications".

If you change a line you did a modification.

[Zach Wegner]

For some it is not about competition, but merely a hobby. By releasing my engine I hope to give a little back to the community and advance the state of computer chess, if only a bit. I have received a lot of help from others as a result of it, so I fully stand by my decision. Personally I think computer chess would be much more boring and at a much lower level if there were no open source engines. I don't know if I would have kept at computer chess at the beginning if I didn't have other programs to look at in order to get past the initial learning curve of writing a completely new engine, especially considering that I was a pretty mediocre programmer at the time.