NAME

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)

# 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.