How to use the command 'tred' (with examples)

The command ’tred’ is used to compute the transitive reduction of directed graphs. It is part of the Graphviz software and can be used to analyze and simplify directed graphs by removing unnecessary edges while preserving the reachability relationships between nodes.

Use case 1: Construct the transitive reduction graph of one or more directed graphs

tred path/to/input1.gv path/to/input2.gv ... > path/to/output.gv

Motivation: This use case is useful when you have one or more directed graphs and you want to compute their transitive reduction. The transitive reduction removes the unnecessary edges in the graph while ensuring that the reachability relationships between nodes are preserved. This can be helpful in simplifying complex graphs and making them easier to analyze.

Explanation:

• tred: This is the command itself that invokes the transitive reduction functionality.
• path/to/input1.gv path/to/input2.gv ...: These are the paths to the input graph files. You can specify multiple graph files separated by a space.
• > path/to/output.gv: This redirects the output of the tred command to a specified output graph file. The transitive reduction graph will be saved in this file.

Example output: Assuming we have two input graph files input1.gv and input2.gv:

$ tred input1.gv input2.gv > output.gv
$ cat output.gv

The output graph file output.gv will contain the transitive reduction graph of input1.gv and input2.gv.

Use case 2: Display help

tred -?

Motivation: This use case is helpful when you want to quickly get information about the usage of the ’tred’ command and its available options. The help option provides a brief overview of the command and its usage.

Explanation:

• tred: This is the command itself that invokes the ’tred’ functionality.
• -?: This is the help option that displays the command usage and available options.

Example output:

$ tred -?
Usage: tred [-l] file
  where file reads a directed graph from stdin (or a named file with option -l),
  and writes its transitive reduction to stdout.

The output displays a brief description of the tred command and how to use it.

Conclusion:

The ’tred’ command is a useful tool for computing the transitive reduction of directed graphs. It allows you to simplify complex graphs by removing unnecessary edges while preserving the reachability relationships between nodes. The command offers a simple and efficient way to analyze and transform directed graphs, making them easier to understand and work with.