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