/usr/ is in acl2-infix-source 7.2dfsg-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/acl2-7.2dfsg/
/usr/lib/acl2-7.2dfsg/books/
/usr/lib/acl2-7.2dfsg/books/interface/
/usr/lib/acl2-7.2dfsg/books/interface/infix/
/usr/lib/acl2-7.2dfsg/books/interface/infix/acl2-formatting.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/infix.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/latex-init.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/latex-theory.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/scribe-init.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/scribe-theory.lisp
/usr/lib/acl2-7.2dfsg/books/interface/infix/sloop.lisp
/usr/share/
/usr/share/doc/
/usr/share/doc/acl2-infix-source/
/usr/share/doc/acl2-infix-source/changelog.Debian.gz
/usr/share/doc/acl2-infix-source/copyright