/usr/share/desktop-directories/Mathematics.directory is in education-menus 1.812+deb8u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | [Desktop Entry]
Name=Mathematics
Name[es]=Matematicas
Name[pt]=Matemáticas
Comment[es]=Aplicaciones didacticas sobre matematicas
Icon=edu-mathematics
Type=Directory
|