source: https://github.com/halostatue/diff-lcs/blob/v1.5.0/License.md

== License

This software is available under three licenses: the GNU GPL version 2 (or at
your option, a later version), the Perl Artistic license, or the MIT license.
Note that my preference for licensing is the MIT license, but Algorithm::Diff
was dually originally licensed with the Perl Artistic and the GNU GPL ("the
same terms as Perl itself") and given that the Ruby implementation originally
hewed pretty closely to the Perl version, I must maintain the additional
licensing terms.

* Copyright 2004–2013 Austin Ziegler.
* Adapted from Algorithm::Diff (Perl) by Ned Konz and a Smalltalk version by
  Mario I. Wolczko.

=== MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

=== Perl Artistic License (version 2)
See the file docs/artistic.txt in the main distribution.

=== GNU GPL version 2
See the file docs/COPYING.txt in the main distribution.