/usr/share/acl2-6.3/books/defexec/ is in acl2-books-certs 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/defexec/dag-unification/
/usr/share/acl2-6.3/books/defexec/dag-unification/basic.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/dag-unification-l.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/dag-unification-rules.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/dag-unification-st.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/dags.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/list-unification-rules.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/matching.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/subsumption-subst.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/subsumption.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/terms-as-dag.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/terms-dag-stobj.cert
/usr/share/acl2-6.3/books/defexec/dag-unification/terms.cert
/usr/share/acl2-6.3/books/defexec/defpun-exec/
/usr/share/acl2-6.3/books/defexec/defpun-exec/defpun-exec.cert
/usr/share/acl2-6.3/books/defexec/find-path/
/usr/share/acl2-6.3/books/defexec/find-path/fpst.cert
/usr/share/acl2-6.3/books/defexec/find-path/graph/
/usr/share/acl2-6.3/books/defexec/find-path/graph/find-path1.cert
/usr/share/acl2-6.3/books/defexec/find-path/graph/find-path2.cert
/usr/share/acl2-6.3/books/defexec/find-path/graph/find-path3.cert
/usr/share/acl2-6.3/books/defexec/find-path/graph/helpers.cert
/usr/share/acl2-6.3/books/defexec/find-path/graph/linear-find-path.cert
/usr/share/acl2-6.3/books/defexec/find-path/run-fpst.cert
/usr/share/acl2-6.3/books/defexec/ordinals/
/usr/share/acl2-6.3/books/defexec/ordinals/supporting-ordinals.cert
/usr/share/acl2-6.3/books/defexec/other-apps/
/usr/share/acl2-6.3/books/defexec/other-apps/misc/
/usr/share/acl2-6.3/books/defexec/other-apps/misc/memos.cert
/usr/share/acl2-6.3/books/defexec/other-apps/misc/stobjsim.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/extraction.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/final-theorem.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/first-last.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/intermediate-program.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/intermediate-to-spec.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/load-extract.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/merge-intermediate.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/nth-update-nth.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/permutations.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/programs.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/sort-qs-properties.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/spec-properties.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/split-qs-properties.cert
/usr/share/acl2-6.3/books/defexec/other-apps/qsort/total-order.cert
/usr/share/acl2-6.3/books/defexec/other-apps/records/
/usr/share/acl2-6.3/books/defexec/other-apps/records/inline.cert
/usr/share/acl2-6.3/books/defexec/other-apps/records/records-bsd.cert
/usr/share/acl2-6.3/books/defexec/other-apps/records/records.cert
/usr/share/acl2-6.3/books/defexec/other-apps/records/recordsim.cert
/usr/share/acl2-6.3/books/defexec/reflexive/
/usr/share/acl2-6.3/books/defexec/reflexive/reflexive.cert