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@wilfwilson wilfwilson released this 15 Feb 11:50
v0.15.0
0592682

This release contains several substantial new features, and some changes to previous functionality.

The most significant change in behaviour is related to the Digraph6 format used in previous versions of the Digraphs package. This method of encoding directed graphs was developed independently from, but concurrently with, the Digraph6 format introduced by nauty; see Issue #158 for more information. The Digraphs package now uses the nauty format, although digraphs encoded using the old format can still be read in. This incompatibility was reported by Jukka Kohonen, and the changes were made by Michael Torpey in PR #162.

Other additions and changes are listed below:

  • A copy of the Edge Addition Planarity Suite is now included in Digraphs, and so it is now possible to test digraphs for planarity, and to perform related computations. This was added by James D. Mitchell in PR #156. The new functionality can be accessed via:
    • Is(Outer)PlanarDigraph,
    • (Outer)PlanarEmbedding,
    • Kuratowski(Outer)PlanarSubdigraph,
    • SubdigraphHomeomorphicToK(23/4/33), and
    • MaximalAntiSymmetricSubdigraph.
  • The functionality and performance for computing homomorphisms of digraphs was significantly improved by James D. Mitchell in PR #160. This PR also introduced the operations EmbeddingsDigraphs and EmbeddingsDigraphsRepresentatives.
  • The one-argument attribute DigraphColouring was renamed to DigraphGreedyColouring, and its performance was improved; it now uses the Welsh-Powell algorithm, which can be accessed directly via DigraphWelshPowellOrder. The behaviour of DigraphGreedyColouring can be modified by including an optional second argument; see the documentation for more information. This work was done by James D. Mitchell in PR #144.
  • DigraphShortestPath was introduced by Murray Whyte in PR #148.
  • IsAntiSymmetricDigraph (with a capital S) was added as a synonym for IsAntisymmetricDigraph.
  • RandomDigraph now allows a float as its second argument; by James D. Mitchell in PR #159.
  • The attribute CharacteristcPolynomial for a digraph was added by Luke Elliott in PR #164.
  • The properties IsVertexTransitive and IsEdgeTransitive for digraphs were added by Graham Campbell in PR #165.
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