tred - Man Page

transitive reduction filter for directed graphs

Examples (TL;DR)


tred [ -vr? ] [ files ]


tred computes the transitive reduction of directed graphs, and prints the resulting graphs to standard output. This removes edges implied by transitivity. Nodes and subgraphs are not otherwise affected. The “meaning” and validity of the reduced graphs is application dependent. tred is particularly useful as a preprocessor to dot to reduce clutter in dense layouts.

Undirected graphs are silently ignored.


The following options are supported:


Verbose output to stderr.


Print information of removed edges to stderr.


Print usage information.


The following operand is supported:


Names of files containing 1 or more graphs in dot format. If no files operand is specified, the standard input will be used.


Using bitmaps internally would substantially decrease running time.


If a graph has cycles, its transitive reduction is not uniquely defined. In this case tred emits a warning.


Stephen C. North <>
Emden R. Gansner <>

See Also

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

Referenced By

acyclic(1), bcomps(1), ccomps(1), gc(1), gvcolor(1), gvgen(1), nop(1), sccmap(1), unflatten(1).

21 March 2001