# License Details

Regina – Software for 3-manifold topology and normal surface theory

Copyright (c) 1999–2014, 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. See here for a suggested form of reference.

### 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 here; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

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.

### External Software

Regina makes use of external software for some specialised tasks. The corresponding license details are included below.

#### 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 written by Jeff Weeks, and SnapPy was written by Marc Culler, Nathan Dunfield, and others. 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, Bogdan Ichim and Christof Soeger. 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.

#### 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 includes code from Source-highlight-qt and language definitions from GNU Source-highlight, which it uses to highlight Python scripts. Both projects are by Lorenzo Bettini and others, and are distributed under the terms of the GNU General Public License, version 3.

#### Icons

The Oxygen icons are dual-licensed under the Creative Common Attribution-ShareAlike 3.0 License or the GNU Library General Public License. The python icons are based on applications-python.svg as shipped with the humanity-icon-theme package in Ubuntu 11.04, the contents of which are licensed under the GNU General Public License version 2.