NAME

       acyclic - make directed graph acyclic

SYNOPSIS

       acyclic [ -nv?  ] [ -o outfile ] [ file ]

DESCRIPTION

       acyclic  is a filter that takes a directed graph as input and outputs a copy of the graph with sufficient
       edges reversed to make the graph acyclic. The reversed  edge  inherits  all  of  the  attributes  of  the
       original  edge. The optional file argument specifies where the the input graph is stored; by default, the
       program reads from stdin.

OPTIONS

       The following options are supported:

       -n     No output is produced, though the return value will indicate whether the graph is acyclic or not.

       -v     Print information about whether the file is acyclic, has a cycle or is undirected.

       -o outfile
              causes the output to be written to the specified file; by default, output is written to stdout.

       -?     option causes the program to print usage information.

RETURN CODES

       acyclic returns 0 if the graph is acyclic; 1 if the graph has a cycle; 2 if the graph is undirected;  and
       255 if there are any errors.

BUGS

       If the graph is strict and there is a cycle of length 2, the attributes of the reversed edge are lost.

       Some  edge  attributes are non-symmetric, referring to either the head or tail node. At present, there is
       no mechanism or convention for correctly switching or renaming these.

AUTHORS

       Stephen C. North <north@research.att.com>
       Emden R. Gansner <erg@research.att.com>

SEE ALSO

       gc(1), dot(1), gvpr(1), gvcolor(1), ccomps(1), sccmap(1), tred(1), libgraph(3)

                                                  21 March 2001                                       ACYCLIC(1)