/usr/ is in cantor-backend-octave 4:4.13.0-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/kde4/apps/
/usr/share/kde4/apps/cantor/
/usr/share/kde4/apps/cantor/octavebackend/
/usr/share/kde4/
/usr/share/kde4/services/
/usr/share/kde4/services/cantor/
/usr/share/kde4/services/cantor/octavebackend.desktop
/usr/lib/
/usr/lib/kde4/
/usr/lib/kde4/cantor_octavebackend.so
/usr/share/
/usr/share/icons/
/usr/share/icons/hicolor/
/usr/share/icons/hicolor/48x48/
/usr/share/icons/hicolor/48x48/apps/
/usr/share/icons/hicolor/48x48/apps/octavebackend.png
/usr/share/kde4/apps/cantor/octavebackend/cantor_plot3d.m
/usr/share/kde4/apps/cantor/octavebackend/cantor_plot2d.m
/usr/share/kde4/apps/cantor/octavebackend/cantor_print.m
/usr/share/kde4/apps/cantor/octavebackend/cantor_eigenvectors.m
/usr/share/kde4/config.kcfg/
/usr/share/kde4/config.kcfg/octavebackend.kcfg
/usr/share/doc/
/usr/share/doc/cantor-backend-octave/
/usr/share/doc/cantor-backend-octave/copyright
/usr/share/doc/cantor-backend-octave/changelog.Debian.gz