NAME

       Graph::Nauty - Perl bindings for Nauty

SYNOPSIS

         use Graph::Nauty qw(
             are_isomorphic
             automorphism_group_size
             canonical_order
             orbits
         );
         use Graph::Undirected;

         my $A = Graph::Undirected->new;
         my $B = Graph::Undirected->new;

         # Create graphs here

         # Get the size of the automorphism group:
         print automorphism_group_size( $A );

         # Get automorphism group orbits:
         print orbits( $A );

         # Check whether two graphs are isomorphs:
         print are_isomorphic( $A, $B );

         # Get canonical order of vertices:
         print canonical_order( $A );

DESCRIPTION

       Graph::Nauty provides an interface to Nauty, a set of procedures for determining the automorphism group
       of a vertex-coloured graph, and for testing graphs for isomorphism.

       Currently Graph::Nauty only supports Graph::Undirected, that is, it does not handle directed graphs. Both
       colored vertices and edges are accounted for when determining equivalence classes.

   Vertex color
       As Graph supports any data types as graph vertices, not much can be inferred about them automatically.
       For now, Graph::Nauty by default stringifies every vertex (using Perl "" operator) and splits them into
       equivalence classes. If different behavior is needed, a custom anonymous subroutine can be passed inside
       an option hash:

         print orbits( $A, sub { return length $_[0] } );

       Subroutine gets a vertex as its 0th parameter, and is expected to return a string, or anything
       stringifiable.

       In subroutines where the order of returned vertices is important, a second anonymous subroutine can be
       passed to order vertices inside each of the equivalence classes:

         print orbits( $A, sub { return length $_[0] }, sub { return "$_[0]" } );

       If an ordering subroutine is not given, stringification (Perl "" operator) is used by default.

   Edge color
       Edge colors are generated from Graph edge attributes. Complete hash of each edge's attributes is
       stringified (deterministically) and used to divide edges into equivalence classes.

   Working storage size
       Nauty needs working storage, which it does not allocate by itself.  Graph::Nauty follows the advice of
       the Nauty user guide by allocating the recommended amount of memory, but for certain graphs this might
       not be enough, still. To control that, $Graph::Nauty::worksize could be used to set the size of memory in
       the units of Nauty's "setword".

INSTALLING

       Building and installing Graph::Nauty from source requires shared library and C headers for Nauty, which
       can be downloaded from <https://users.cecs.anu.edu.au/~bdm/nauty/>. Both the library and C headers have
       to be installed to locations visible by Perl's C compiler.

SEE ALSO

       For the description of Nauty refer to <http://pallini.di.uniroma1.it>.

AUTHOR

       Andrius Merkys, <mailto:merkys@cpan.org>

COPYRIGHT AND LICENSE

       Copyright (C) 2020 by Andrius Merkys

       Graph::Nauty is distributed under the BSD-3-Clause license.