mathematical software for low-dimensional topology

 Regina is a software package for 3-manifold and 4-manifold topologists,
 with a focus on triangulations, knots and links, normal surfaces, and
 angle structures.
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 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.
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 Regina comes with a full graphical user interface, as well as Python bindings
 and a low-level C++ programming interface.
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 This package includes the graphical user interface and the command-line
 Python interface. The users' handbook and the API documentation are in
 the separate package regina-normal-doc.