gap-core software package provides GAP computer algebra system, core components, 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 gap-core
gap-core is installed in your system.
Make ensure the gap-core package were installed using the commands given below,
$ sudo dpkg-query -l | grep gap-core *
You will get with gap-core package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Mathematics |
| Package | gap-core |
| Version | 4r8p5-1 |
| Description | GAP computer algebra system, core components |
| Sub Section | Math |