i wonder how much of that original Kibana code remains today (my guess is not very much), and if it were originally AGPL, would a completely rewritten codebase still be subject to it?
The license talk about derived work. And even if every line of code has been changed, it is still a derived work as it was progressively changed. So pattern and desings from the original are still in use. The Ship of Theseus is still the Ship of Theseus.
> The Ship of Theseus is still the Ship of Theseus.
you state this as if it's a settled fact (it isn't).
If you take a Shakespeare novel and replace every word in it with another word, and then remove and add many chapters to it, then shuffle all the pages, is it still a Shakespeare work or even recognizable as being derived from one? I think most would say "no".
In the case of Ship of Theseus, if you replaced every part with a different looking part, removed 30% of the parts entirely and added another 300% parts such that the function was expanded by 1,000%, would anyone recognize it as the same thing?
There has to be _some_ threshold beyond which you cannot reasonably claim the work is derivative.
If version B is modified from version A as a derivative work (therefore licensed as A) and version C is modified from version B as a derivative work of B, then would C not still be licensed same as B, and therefore A?
It seems it depends on how you view the accumulation of differences. If your only comparison is always against version A, then yes, eventually there must be enough accumulation of differences that one could claim a work is no longer derivative. But if you consider all versions between A and yours, then suddenly its just a series of gradual changes, none of which individually cause the work to become non-derivative. The Ship of Theseus parable seems to also fit this latter interpretation more -- it is after all about replacing items one at a time.
I agree with you from a practical legal point though. My argument above seems to imply that there's only been derived work since the first cell split in two. In practice this would be a nightmare; There should be a threshold whereupon a work can qualify on its own merits.
> it is still a derived work as it was progressively changed.
I think that depends. If it was progressively changed to something completely different, then, no.
Let's say in 10 days you replaced 10% of the code, with the same amount of code from a different program by another author. During those 10 days there'd be compilation errors, and thereafter the original work and copyright would be all gone (except for in old revisions in the repo), and the copyright holder of the new program could license it however s/he wanted.
It is still likely a derived work. Looks more to me in the example it was just practised the right to make changes to the original work which one could do under the given circumstances which is normally a reciprocal license - floss or else - which means even when if 100% of all letters in all files have been changed, one could still not do more than the original license granted.
and that is normally _not_ what you wrote:
> the copyright holder [sic!] of the new program could license it however s/he wanted.
However if sole copyright holder - real, not imagined - she sure can license it - or not. Or different another day.
