Bug #62626 for Graph: Graph::TransitiveClosure::Matrix contradictory wrt reflexive

Mon Nov 01 16:32:45 2010 derhoermi [...] gmx.net - Ticket created

Subject:	Graph::TransitiveClosure::Matrix contradictory wrt reflexive
Date:	Mon, 01 Nov 2010 21:32:35 +0100
To:	bug-graph [...] rt.cpan.org
From:	Bjoern Hoehrmann <derhoermi [...] gmx.net>

Hi, For 0.94, in the synopsis it says "Being reflexive is the default" while the documentation for the reflexive option says "By default the transitive closure matrix is not reflexive" (and in 0.91 the default appears to be reflexive, haven't checked 0.94). regards, -- Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de Am Badedeich 7 · Telefon: +49(0)160/4415681 · http://www.bjoernsworld.de 25899 Dagebüll · PGP Pub. KeyID: 0xA4357E78 · http://www.websitedev.de/

Fri Jun 10 10:07:51 2011 ynnor [...] mm.st - Correspondence added

From:

ynnor [...] mm.st

On Mon Nov 01 16:32:45 2010, derhoermi@gmx.net wrote: Show quoted text

> For 0.94, in the synopsis it says "Being reflexive is the default" > while the documentation for the reflexive option says "By default the > transitive closure matrix is not reflexive" (and in 0.91 the default > appears to be reflexive, haven't checked 0.94).

Same in 0.94. The documentation says on one point "is_reachable is always reflexive", and in a different place it says that is_reachable would be the same as has_edge (which means it is NOT reflexive for directed graphs. In fact, is_transitive($u,$g) seems to do the job.

Fri Jun 10 10:07:52 2011 The RT System itself - Status changed from 'new' to 'open'

Fri Jun 10 10:28:23 2011 ynnor [...] mm.st - Correspondence added

From:

ynnor [...] mm.st

I need to correct my last post. is_transitive doesn't work either. Although the documentation says: ======= # The reflexivity of is_transitive(u, v) depends of the reflexivity # of the transitive closure. $tcg->is_transitive($u, $v) ======= is_transitive always ignores its arguments and just returns the transitivity of the whole graph.

Fri Jun 10 10:32:33 2011 ynnor [...] mm.st - Correspondence added

From:

ynnor [...] mm.st

Example program to demonstrate the bug: Although the add_edge line has been commented out (i.e. the graph consists only of 2 isolated notes), is_transitive(1,2) returns true. ==================================================== use strict; use warnings; use Graph; use Graph::TransitiveClosure; my $g=Graph->new; for my $n (1..2) { $g->add_vertex($n) } # $g->add_edge(1,2); print "$g\n"; my $tcg=Graph::TransitiveClosure->new($g,reflexive => 1); for my $n (1..2) { my $z=3-$n; print "is_transitive($n,$z) is ",$tcg->is_transitive($n,$z) ? 'true' : 'false',"\n"; }

Mon Sep 21 20:00:37 2015 JHI [...] cpan.org - Correspondence added

I think this is mostly a documentation bleargh. is_transitive() is not meant for testing reachability: is_reachable() is.

Mon Sep 21 20:00:43 2015 JHI [...] cpan.org - Status changed from 'open' to 'resolved'