/usr/share/acl2-6.3/books/proofstyles/ is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/proofstyles/completeness/
/usr/share/acl2-6.3/books/proofstyles/completeness/assertions-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/assertions-total.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/clock-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/clock-total.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/generic-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/generic-total.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/stepwise-invariants-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/completeness/stepwise-invariants-total.lisp
/usr/share/acl2-6.3/books/proofstyles/counterexamples/
/usr/share/acl2-6.3/books/proofstyles/counterexamples/halt-flg.lisp
/usr/share/acl2-6.3/books/proofstyles/counterexamples/memory-clearing.lisp
/usr/share/acl2-6.3/books/proofstyles/counterexamples/realistic.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/
/usr/share/acl2-6.3/books/proofstyles/invclock/c2i/
/usr/share/acl2-6.3/books/proofstyles/invclock/c2i/c2i-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/c2i/c2i-total.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/c2i/clock-to-inv.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/compose/
/usr/share/acl2-6.3/books/proofstyles/invclock/compose/compose-c-c-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/compose/compose-c-c-total.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/i2c/
/usr/share/acl2-6.3/books/proofstyles/invclock/i2c/i2c-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/i2c/i2c-total.lisp
/usr/share/acl2-6.3/books/proofstyles/invclock/i2c/inv-to-clock.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/
/usr/share/acl2-6.3/books/proofstyles/soundness/assertions-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/assertions-total.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/clock-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/clock-total.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/stepwise-invariants-partial.lisp
/usr/share/acl2-6.3/books/proofstyles/soundness/stepwise-invariants-total.lisp