/usr/share/acl2-6.3/books/ihs/ is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/ihs/@logops.lisp
/usr/share/acl2-6.3/books/ihs/basic-definitions.lisp
/usr/share/acl2-6.3/books/ihs/ihs-definitions.lisp
/usr/share/acl2-6.3/books/ihs/ihs-doc-topic.lisp
/usr/share/acl2-6.3/books/ihs/ihs-init.acl2
/usr/share/acl2-6.3/books/ihs/ihs-init.lisp
/usr/share/acl2-6.3/books/ihs/ihs-lemmas.lisp
/usr/share/acl2-6.3/books/ihs/ihs-theories.lisp
/usr/share/acl2-6.3/books/ihs/logops-definitions.lisp
/usr/share/acl2-6.3/books/ihs/logops-lemmas.lisp
/usr/share/acl2-6.3/books/ihs/math-lemmas.lisp
/usr/share/acl2-6.3/books/ihs/quotient-remainder-lemmas.lisp