---
name: "tred"
section: "1"
platform: "linux"
package: "graphviz"
version: "16.1.0-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/tred"
---

# tred(1)

transitive reduction filter for directed graphs

## NAME

tred - transitive reduction filter for directed graphs

## SYNOPSIS

**tred** \[ **-ovr?** \] \[ *files* \]

## DESCRIPTION

**tred** computes the transitive reduction of directed graphs, and prints the resulting graphs to a file or 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.

## OPTIONS

The following options are supported:

- **-o FILE**

  Redirect output to the given file. By default, output goes to stdout.

- **-v**

  Verbose output to stderr.

- **-r**

  Print information of removed edges to stderr.

- **-?**

  Print usage information.

## OPERANDS

The following operand is supported:

- *files*

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

## BUGS

Using bitmaps internally would substantially decrease running time.

## DIAGNOSTICS

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

## AUTHORS

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

## SEE ALSO

[gc(1)](/gc/1.md), [dot(1)](/dot/1.md), [acyclic(1)](/acyclic/1.md), [gvpr(1)](/gvpr/1.md), [gvcolor(1)](/gvcolor/1.md), [ccomps(1)](/ccomps/1.md), [sccmap(1)](/sccmap/1.md), libgraph(3)