/usr/share/acl2-6.3/books/centaur/aignet/ is in acl2-books-certs 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/centaur/aignet/aig-cnf.cert
/usr/share/acl2-6.3/books/centaur/aignet/aig-sim.cert
/usr/share/acl2-6.3/books/centaur/aignet/aignet-absstobj.cert
/usr/share/acl2-6.3/books/centaur/aignet/aignet-exec-thms.cert
/usr/share/acl2-6.3/books/centaur/aignet/aignet-exec.cert
/usr/share/acl2-6.3/books/centaur/aignet/aignet-logic-interface.cert
/usr/share/acl2-6.3/books/centaur/aignet/aignet-logic.cert
/usr/share/acl2-6.3/books/centaur/aignet/arrays.cert
/usr/share/acl2-6.3/books/centaur/aignet/bit-lemmas.cert
/usr/share/acl2-6.3/books/centaur/aignet/cnf.cert
/usr/share/acl2-6.3/books/centaur/aignet/construction.cert
/usr/share/acl2-6.3/books/centaur/aignet/copying.cert
/usr/share/acl2-6.3/books/centaur/aignet/eval.cert
/usr/share/acl2-6.3/books/centaur/aignet/from-hons-aig.cert
/usr/share/acl2-6.3/books/centaur/aignet/litp.cert
/usr/share/acl2-6.3/books/centaur/aignet/portcullis.cert
/usr/share/acl2-6.3/books/centaur/aignet/prune.cert
/usr/share/acl2-6.3/books/centaur/aignet/refcounts.cert
/usr/share/acl2-6.3/books/centaur/aignet/semantics.cert
/usr/share/acl2-6.3/books/centaur/aignet/snodes.cert
/usr/share/acl2-6.3/books/centaur/aignet/to-hons-aig.cert
/usr/share/acl2-6.3/books/centaur/aignet/types.cert
/usr/share/acl2-6.3/books/centaur/aignet/vecsim.cert