wolffd@0: .TH ACYCLIC 1 "21 March 2001"
wolffd@0: .SH NAME
wolffd@0: acyclic \- make directed graph acyclic
wolffd@0: .SH SYNOPSIS
wolffd@0: .B acyclic
wolffd@0: [
wolffd@0: .B \-nv?
wolffd@0: ] [
wolffd@0: .B \-o
wolffd@0: .I outfile
wolffd@0: ]
wolffd@0: [ 
wolffd@0: .I file
wolffd@0: ]
wolffd@0: .SH DESCRIPTION
wolffd@0: .B acyclic
wolffd@0: is a filter that takes a directed graph as input and outputs
wolffd@0: a copy of the graph with sufficient edges reversed to make
wolffd@0: the graph acyclic. The reversed edge inherits all of the attributes
wolffd@0: of the original edge. The optional file argument specifies where the
wolffd@0: the input graph is stored; by default, the program reads from \fBstdin\fP.
wolffd@0: .SH OPTIONS
wolffd@0: The following options are supported:
wolffd@0: .TP
wolffd@0: .B \-n
wolffd@0: No output is produced, though the return value
wolffd@0: will indicate whether the graph is acyclic or not.
wolffd@0: .TP
wolffd@0: .B \-v
wolffd@0: Print information about whether the file is acyclic, has a cycle or
wolffd@0: is undirected.
wolffd@0: .TP
wolffd@0: .BI \-o " outfile"
wolffd@0: causes the output to be written to the specified file; by default,
wolffd@0: output is written to \fBstdout\fP.
wolffd@0: .TP
wolffd@0: .B \-?
wolffd@0: option causes the program to print usage information.
wolffd@0: .SH RETURN CODES
wolffd@0: .B acyclic
wolffd@0: returns
wolffd@0: .B 0
wolffd@0: if the graph is acyclic;
wolffd@0: .B 1
wolffd@0: if the graph has a cycle;
wolffd@0: .B 2
wolffd@0: if the graph is undirected; and
wolffd@0: .B 255
wolffd@0: if there are any errors.
wolffd@0: .SH BUGS
wolffd@0: If the graph is strict and there is a cycle of length 2, 
wolffd@0: the attributes of the reversed edge are lost.
wolffd@0: .PP
wolffd@0: Some edge attributes are non-symmetric, referring to either the head
wolffd@0: or tail node. At present, there is no mechanism or convention for
wolffd@0: for correctly switching or renaming these.
wolffd@0: .SH AUTHORS
wolffd@0: Stephen C. North <north@research.att.com>
wolffd@0: .br
wolffd@0: Emden R. Gansner <erg@research.att.com>
wolffd@0: .SH "SEE ALSO"
wolffd@0: gc(1), dot(1), gvpr(1), gvcolor(1), ccomps(1), sccmap(1), tred(1), libgraph(3)