[Xapian-devel] Adding Support for Krovetz Stemmer Algo in Xapian

[Olly Betts]

On Sun, Nov 30, 2014 at 03:28:35PM +0000, James Aylett wrote:
> On 29 Nov 2014, at 15:34, Abhishek Singh Kushwah <abhishek18kushwah at gmail.com> wrote:
> > i found an implementation of Krovetz Stemmer Algo in C++ but before
> > working on it to merge it into xapian, i needed help in recognizing
> > the license information associated with the source code.
> > 
> > To avoid further licensing issues kindly someone check the link 
> > 
> > http://sourceforge.net/p/lemur/wiki/KrovetzStemmer/  
> 
> The project suggests it’s under a BSD license, but the code itself is
> a mire of confusion, citing that license (by URL), and an “all rights
> reserved” copyright statement underneath. Since the BSD license grant
> is for “use of the Lemur Toolkit…” I don’t think we can reasonably
> assume that the individual code is actually licensed appropriately for
> us to use.

I think a bigger issue is that this licence is actually a variant of the
BSD licence which is probably GPL-incompatible.

Here's the two licences to compare:

http://www.lemurproject.org/license.html
http://directory.fsf.org/wiki/License:BSD_3Clause

Clauses 1 and 2 are the same, the capitalised disclaiming
of warranties is the same except for "AUTHOR" being substituted, and 3
is similar but with "author" substituted and some rewording.

But the added clause 4 is problematic as it renders the licence
incompatible with the GPL.  It's essentially the same as clause 4
of the PHP licence:

http://php.net/license/3_01.txt

And that clause apparently is a strong restriction on naming derived
products:

http://www.gnu.org/licenses/license-list.html#PHP-3.01

Cheers,
    Olly