LICENSE.txt

               Regina - Software for low-dimensional topology
            Copyright (c) 1999-2023, The Regina development team


CITATION:

If you find Regina useful in your research, please consider citing it as
you would any other paper that you use.  A suggested form of reference is:

  Benjamin A. Burton, Ryan Budney, William Pettersson, et al.,
  "Regina: Software for low-dimensional topology",
  http://regina-normal.github.io/, 1999-2023.


AUTHORS:

The primary developers of Regina are:

  Benjamin Burton <bab@maths.uq.edu.au>
  Ryan Budney <rybu@uvic.ca>
  William Pettersson <william.pettersson@gmail.com>

Many others have been of assistance with this project, be it through time,
knowledge, testing or code.  Please see the full list of acknowledgements
in the users' handbook.


COPYING AND MODIFICATION:

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

Some of this code comes with additional permissions; see the section
below regarding online distribution.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

A full copy of the GNU General Public License should be included below;
if not, write to the Free Software Foundation, Inc., 51 Franklin St,
Fifth Floor, Boston, MA 02110-1301, USA.


ONLINE DISTRIBUTION:

Regina's own source code comes with the following permissions in
addition to the GNU General Public License:

As an exception, when this program is distributed through (i) the
App Store by Apple Inc.; (ii) the Mac App Store by Apple Inc.; or
(iii) Google Play by Google Inc., then that store may impose any
digital rights management, device limits and/or redistribution
restrictions that are required by its terms of service.

Some third-party libraries included in Regina are not granted this
exception, and must be removed from any build that is distributed on
stores that cannot comply with the GNU General Public License (such as
Apple's App Store).  See the third-party licenses below for details.


SNAPPEA AND SNAPPY:

Regina includes portions of the SnapPea kernel and its successor SnapPy,
which it uses for some geometric calculations.  The SnapPea kernel was
originally written by Jeff Weeks.  SnapPy, where this kernel is now maintained,
is primarily developed by Marc Culler, Nathan Dunfield and Matthias Goerner,
with contributions from many people.  SnapPy and the corresponding SnapPea
kernel are distributed under the terms of the GNU General Public License,
version 2 or any later version, as published by the Free Software Foundation.


NORMALIZ LIBRARY:

Regina includes a copy of libnormaliz, which it uses to help with the
enumeration of fundamental normal surfaces.  Normaliz was written by Winfried
Bruns, Christof Soeger and others.  It is distributed under the terms of
the GNU General Public License as published by the Free Software Foundation,
either version 3 of the License, or (at your option) any later version.


PYBIND11:

Regina includes a copy of pybind11, which it uses to generate python bindings
for Regina's native C++ code.  The pybind11 library was written by
Wenzel Jakob, and is distributed under a BSD-style license that is shipped
with Regina's source code in the file python/pybind11/LICENSE.


PYTHON RLCOMPLETER MODULE:

Regina includes a modified copy of the Python rlcompleter module, which it
uses for tab completion in the graphical user interface.  The original
rlcompleter module was distributed under the Python Software Foundation
License Version 2; the full license and copyright notice are shipped with
Regina's source code in the file python/regina/LICENSE.


ORB KERNEL:

Regina includes snippets of code from Orb, for use in importing and
exporting files in Orb / Casson format.  Orb is based on SnapPea
(see above) with additional code written by Damian Heard, who has also
given permission for his code to be distributed under the terms of the
GNU General Public License.


SYNTAX HIGHLIGHTING:

Regina's graphical user interfaces incorporate a modified version of the KDE
syntax-highlighting framework, which they use for highlighting Python scripts.
This framework is distributed under the GNU Library General Public License,
version 2 or any later version, as published by the Free Software Foundation.


ICONS:

Many of Regina's icons are custom-made, and are under the same license as
Regina.  Some system icons are taken from the Humanity icon set (licensed
under the GNU General Public License version 2) and the Oxygen icon set
(licensed under the GNU Lesser General Public License version 3 or later).
Regina's die icon is based on an image from openclipart.org, which has been
released into the public domain.


GOOGLETEST:

Regina includes a copy of GoogleTest, which it uses as a framework for the
C++ test suite.  GoogleTest is copyright by Google Inc., and is distributed
under a BSD-style license that is shipped with Regina's source code in the
file engine/testsuite/gtest/LICENSE.



                    GNU GENERAL PUBLIC LICENSE
                       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
        51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

                            Preamble

  The licenses for most software are designed to take away your
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  When we speak of free software, we are referring to freedom, not
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  To protect your rights, we need to make restrictions that forbid
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  The precise terms and conditions for copying, distribution and
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                    GNU GENERAL PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
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These requirements apply to the modified work as a whole.  If
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Thus, it is not the intent of this section to claim rights or contest
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In addition, mere aggregation of another work not based on the Program
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                            NO WARRANTY

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                     END OF TERMS AND CONDITIONS

            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA


Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year  name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
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be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
  `Gnomovision' (which makes passes at compilers) written by James Hacker.

  <signature of Ty Coon>, 1 April 1989
  Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.