/usr/share/acl2-7.1/books/demos/ is in acl2-books-source 7.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-7.1/books/demos/constants-that-require-modifying-state.lisp
/usr/share/acl2-7.1/books/demos/gl-and-use-example.acl2
/usr/share/acl2-7.1/books/demos/gl-and-use-example.lisp
/usr/share/acl2-7.1/books/demos/knuth-bendix-problem-1.lisp
/usr/share/acl2-7.1/books/demos/list-theory.lisp
/usr/share/acl2-7.1/books/demos/modeling/
/usr/share/acl2-7.1/books/demos/modeling/cert.acl2
/usr/share/acl2-7.1/books/demos/modeling/memories.lisp
/usr/share/acl2-7.1/books/demos/modeling/nested-stobj-toy-isa.acl2
/usr/share/acl2-7.1/books/demos/modeling/nested-stobj-toy-isa.lisp
/usr/share/acl2-7.1/books/demos/modeling/network-state-basic.lisp
/usr/share/acl2-7.1/books/demos/modeling/network-state.lisp
/usr/share/acl2-7.1/books/demos/modeling/nondeterminism.lisp
/usr/share/acl2-7.1/books/demos/parallel/
/usr/share/acl2-7.1/books/demos/parallel/fibonacci.lisp
/usr/share/acl2-7.1/books/demos/parallel/matrix-multiplication-parallel.lisp
/usr/share/acl2-7.1/books/demos/parallel/matrix-multiplication-serial.lisp
/usr/share/acl2-7.1/books/demos/parallel/matrix-multiplication-setup.lisp
/usr/share/acl2-7.1/books/demos/patterned-congruences.lisp
/usr/share/acl2-7.1/books/demos/proofs/
/usr/share/acl2-7.1/books/demos/proofs/linear.lisp
/usr/share/acl2-7.1/books/demos/proofs/type-prescription.lisp
/usr/share/acl2-7.1/books/demos/split-types-examples.lisp
/usr/share/acl2-7.1/books/demos/tutorial-problems/
/usr/share/acl2-7.1/books/demos/tutorial-problems/equivalence-of-two-functions/
/usr/share/acl2-7.1/books/demos/tutorial-problems/equivalence-of-two-functions/kaufmann.lisp
/usr/share/acl2-7.1/books/demos/tutorial-problems/equivalence-of-two-functions/moore.lisp
/usr/share/acl2-7.1/books/demos/tutorial-problems/introductory-challenge-problem-4-athena.lisp
/usr/share/acl2-7.1/books/demos/tutorial-problems/introductory-challenge-problem-4.lisp