/usr/share/acl2-6.3/books/arithmetic-3/bind-free/ is in acl2-books-certs 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/arithmetic-theory.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/banner.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/basic-helper.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/basic.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/building-blocks.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/collect.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/common.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/default-hint.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/integerp-meta.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/integerp.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/mini-theories-helper.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/mini-theories.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/normalize.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/numerator-and-denominator.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/remove-weak-inequalities.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/simplify-helper.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/simplify.cert
/usr/share/acl2-6.3/books/arithmetic-3/bind-free/top.cert