News

18 March 2023: Regina 7.3.1 is out! This is a service release that fixes some important bugs, and adds support for Python 3.12 and later. You can read all about what's new, or just go ahead and download it.

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What is Regina?

For 3-manifolds, it includes high-level tasks such as 3-sphere recognition, connected sum decomposition and Hakenness testing, comes with a rich database of census manifolds, and incorporates the SnapPea kernel for working with hyperbolic manifolds. For 4-manifolds, it offers a range of combinatorial and algebraic tools, plus support for normal hypersurfaces. For knots and links, Regina can perform combinatorial manipulation, compute knot polynomials, and work with several import/export formats.

Regina comes with a full graphical user interface, as well as Python bindings and a low-level C++ programming interface.

See the users' handbook for a detailed list of features.

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Screenshots

Studying 3-manifold triangulations	Normal surfaces and angle structures
Knots and links	In-built Python scripting

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Download

The following downloads are available:

Mac Windows GNU/Linux PyPI / SageMath iPad Source code

All direct downloads come with SHA-1 checksums and SHA-256 checksums, signed with Ben Burton's GPG key.

If you encounter any problems when you run Regina, you can check the troubleshooting page to see if your problem is discussed there. You also most welcome to contact us for help.

Mac

You can download Regina either from this website, or via the App Store (for free of course). Not sure which? Start with the App Store version (but read below).

macOS version		Website download	App store
Ventura (13) Monterey (12) Big Sur (11) Catalina (10.15)		Download here

There are some minor differences between the website and App Store versions. The App Store version:

• means that macOS will notify you of upgrades;
• may support iCloud in a future release (which is not possible for a website download);
• is sandboxed for extra security, which limits file access through Python and the command-line tools (see below).

Sandboxing is a security measure that comes with all App Store downloads: it ensures that apps only access files that you explicitly choose through the graphical file dialogs (Open, Save, etc.). For Regina, this means that when you open a Python console or run command-line tools (regina-python, regfiledump, etc.), the only personal files you can access are those in your Downloads folder. You can still access world-readable files, such as those in your Applications folder.

Windows

Regina now only supports 64-bit Windows, and only on Intel/AMD64 chipsets. Almost all modern Windows installations are of this type, and so this is almost certainly the version that you want.

If you still have an ancient 32-bit Windows system and you need to get Regina running on it, please let Ben know. If your machine has an ARM64 chipset (e.g., you have a Mac with Apple Silicon), you will need to run Regina under a different operating system (e.g., macOS or GNU/Linux).

Windows version		Installer
Windows 11 Windows 10		Coming shortly! Check here again in a couple of days.

When running the installer you may see a security warning, such as “Microsoft Defender SmartScreen prevented an unrecognized app from starting ...”, or a message from SmartScreen Filter that “This program might harm your computer”. This is because Microsoft has not added Regina to its database of known applications. Click More info or More options and you should be able to run the installer anyway.

GNU/Linux

For instructions on setting up Regina's package repositories, click on the Install link for your system in the table below.

Regina's GNU/Linux packages are named regina-normal (to avoid conflicting with the other Regina).

Distribution		Versions	Architectures	Instructions
Arch Linux		Rolling release	x86_64	Coming in a few days
Debian		12.x (bookworm) 11.x (bullseye)	amd64 arm64 i386	Install
		unstable (sid)	Everything
Fedora		42 41	aarch64 x86_64	Install
openSUSE		Leap 15.6	aarch64 x86_64	Install
Ubuntu		25.04 (plucky) 24.10 (oracular) 24.04 LTS (noble) 22.04 LTS (jammy)	amd64 arm64	Install

Architectures:

• You do not need to know what architecture you have; the online repositories will work this out for you automatically.
• For reference, amd64/x86_64 refers to 64-bit Intel machines, arm64/aarch64 refers to 64-bit ARM machines (including Apple Silicon), and i386 refers to very old 32-bit Intel machines. Together these cover almost any typical desktop or laptop nowadays.
• If you have a particularly exotic chipset, try the Debian unstable packages, which are built for every architecture in Debian.

For older versions of GNU/Linux:

• If your distribution is in the table above but your version is too old, then your version of GNU/Linux may have passed its end-of-life. This is a security risk, since most distributions do not provide security updates for old (end-of-life) versions. You should seriously consider upgrading your machine.

For newer versions of GNU/Linux:

• If your distribution is in the table above but your version is too new, then drop Ben an email and he should be able to upload a package for you. Otherwise you can always build from source (see below).

For other GNU/Linux distributions:

• If you are using some other distribution (e.g., RedHat, Slackware, …), then you will need to build Regina from source.

System		Instructions
PyPI		Install

Of course, whilst the packages are written to work with any modern version of SageMath, your experiences might vary (particular with an older SageMath and/or operating system). Follow the instructions link above for details.

iPad

For other systems not listed above, you will need to build Regina from its source code.

You can download the source code here.

Please see the separate page on building Regina for instructions on how to build Regina and what libraries and tools you will need to have installed.

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Documentation

Users' Handbook

You can read the handbook from within Regina by selecting Help → Regina Handbook from the menu. You can also read it here online.

Python/C++ API Documentation

You can read the API documentation by:

• selecting Help → Python API Reference from the menu;
• reading it here online;
• getting inline help directly within Python via docstrings (but please see the handbook for the limits of what these docstrings can and cannot provide).

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What's new in version 7.3.1?

Regina 7.3.1 is a service release to fix some important bugs, and to support Python 3.12 and later. Python 3.6 is no longer supported.

Bugs fixed:

• Manually resolving a crossing in a link would not clear out cached polynomials that had already been computed for that link. See here for details.
• Manually setting a coefficient in a Laurent polynomial in C++/Python would, in special circumstances, have no effect. This did not affect the GUI or any Jones polynomial computations. See here for details.
• If a normal surface was a normalised triangle link but not a thin triangle link, then using C++/Python to call isThinTriangleLink() before isNormalTriangleLink() would make the latter return an empty list of results. Likewise with tetrahedron links in 4-dimensional triangulations. This did not affect the GUI. See here for details.
• If the connectness of a normal surface had already been computed, then calling NormalSurface.components() in C++/Python would return the entire surface as a single component. This did not affect the GUI. See here for details.
• Fixed some less important problems also: see the full changelog for details.

Other improvements:

• Improved the speed of iteration in Python (specifically, throwing/catching StopIteration exceptions).

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Announcement Mailing List

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License and Citation

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.

Citation

Benjamin A. Burton, Ryan Budney, William Pettersson, et al.,
Regina: Software for low-dimensional topology,
http://regina-normal.github.io/, 1999–2025.

@misc{regina,
    author = {Benjamin A. Burton and Ryan Budney and William Pettersson and others},
    title = {Regina: Software for low-dimensional topology},
    howpublished = {{\tt http://\allowbreak regina-normal.\allowbreak github.\allowbreak io/}},
    year = {1999--2025}}

Copying & 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, which allow it to be distributed through online repositories such as Apple's App Store or Google Play. See the full license in the users' handbook for details.

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.

Detailed License

For complete license details, including the full GNU General Public License and information on external software that Regina uses, see the full license in the users' handbook.

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Contact

If you have written your own extensions that you think could be worth putting in the main release, please do write and let us know.

Even if you have no comments to make, it's always nice to hear from people using Regina, even if it's just to say hi. We're always interested to hear how this software is being used.

You can contact us by email: our websites are linked to our names in the author list above.

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Privacy Policy

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