cliquer software package provides clique searching program, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install cliquer
cliquer is installed in your system.
Make ensure the cliquer package were installed using the commands given below,
$ sudo dpkg-query -l | grep cliquer *
You will get with cliquer package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Mathematics |
| Package | cliquer |
| Version | 1.21-1+b1 [armhf], 1.21-1 [amd |
| Description | clique searching program |
| Sub Section | Math |