/usr/lib/swi-prolog/library/chr/ is in swi-prolog-nox 6.6.4-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/swi-prolog/library/chr/README
/usr/lib/swi-prolog/library/chr/a_star.pl
/usr/lib/swi-prolog/library/chr/binomialheap.pl
/usr/lib/swi-prolog/library/chr/builtins.pl
/usr/lib/swi-prolog/library/chr/chr_compiler_errors.pl
/usr/lib/swi-prolog/library/chr/chr_compiler_options.pl
/usr/lib/swi-prolog/library/chr/chr_compiler_utility.pl
/usr/lib/swi-prolog/library/chr/chr_debug.pl
/usr/lib/swi-prolog/library/chr/chr_hashtable_store.pl
/usr/lib/swi-prolog/library/chr/chr_integertable_store.pl
/usr/lib/swi-prolog/library/chr/chr_messages.pl
/usr/lib/swi-prolog/library/chr/chr_op.pl
/usr/lib/swi-prolog/library/chr/chr_runtime.pl
/usr/lib/swi-prolog/library/chr/chr_translate.pl
/usr/lib/swi-prolog/library/chr/clean_code.pl
/usr/lib/swi-prolog/library/chr/find.pl
/usr/lib/swi-prolog/library/chr/guard_entailment.pl
/usr/lib/swi-prolog/library/chr/listmap.pl
/usr/lib/swi-prolog/library/chr/pairlist.pl