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Graph::TransitiveClosure.3pm

Graph::TransitiveClosure - create and query transitive closure of graph

SYNOPSIS

     use Graph::TransitiveClosure;
     use Graph::Directed; # or Undirected
 
     my $g  = Graph::Directed->new;
     $g->add_...(); # build $g
 
     # Compute the transitive closure graph.
     my $tcg = Graph::TransitiveClosure->new($g);
     $tcg->is_reachable($u, $v) # Identical to $tcg->has_edge($u, $v)
 
     # Being reflexive is the default, meaning that null transitions
     # (transitions from a vertex to the same vertex) are included.
     my $tcg = Graph::TransitiveClosure->new($g, reflexive => 1);
     my $tcg = Graph::TransitiveClosure->new($g, reflexive => 0);
 
     # is_reachable(u, v) is always reflexive.
     $tcg->is_reachable($u, $v)
 
     # The reflexivity of is_transitive(u, v) depends of the reflexivity
     # of the transitive closure.
     $tcg->is_transitive($u, $v)
 
     # You can check any graph for transitivity.
     $g->is_transitive()
 
     my $tcg = Graph::TransitiveClosure->new($g, path_length => 1);
     $tcg->path_length($u, $v)
 
     # path_vertices is automatically always on so this is a no-op.
     my $tcg = Graph::TransitiveClosure->new($g, path_vertices => 1);
     $tcg->path_vertices($u, $v)
 
     # Both path_length and path_vertices.
     my $tcg = Graph::TransitiveClosure->new($g, path => 1);
     $tcg->path_vertices($u, $v)
     $tcg->length($u, $v)
 
     my $tcg = Graph::TransitiveClosure->new($g, attribute_name => 'length');
     $tcg->path_length($u, $v)
 
 

DESCRIPTION

You can use "Graph::TransitiveClosure" to compute the transitive closure graph of a graph and optionally also the minimum paths (lengths and vertices) between vertices, and after that query the transitiveness between vertices by using the "is_reachable()" and "is_transitive()" methods, and the paths by using the "path_length()" and "path_vertices()" methods.

For further documentation, see the Graph::TransitiveClosure::Matrix.

Class Methods

new($g, %opt)

Construct a new transitive closure object. Note that strictly speaking the returned object is not a graph; it is a graph plus other stuff. But you should be able to use it as a graph plus a couple of methods inherited from the Graph::TransitiveClosure::Matrix class.

Object Methods

These are only the methods 'native' to the class: see Graph::TransitiveClosure::Matrix for more.

is_transitive($g)

Return true if the Graph $g is transitive.

transitive_closure_matrix

Return the transitive closure matrix of the transitive closure object.

INTERNALS

The transitive closure matrix is stored as an attribute of the graph called "_tcm", and any methods not found in the graph class are searched in the transitive closure matrix class.