| contains_term/2 | Succeeds if Sub is contained in Term (=, deterministically). |
| contains_var/2 | Succeeds if Sub is contained in Term (==, deterministically). |
| free_of_term/2 | Succeeds of Sub does not unify to any subterm of Term. |
| free_of_var/2 | Succeeds
of Sub is not equal (==) to any subterm of Term. |
| occurrences_of_term/3 | Count the number of SubTerms in Term. |
| occurrences_of_var/3 | Count the number of SubTerms in Term. |
| sub_term/2 | Generates (on backtracking) all subterms of Term. |
| sub_term_shared_variables/3 | If Sub is a sub term of Term, Vars is bound to the list of variables in Sub that also appear outside Sub in Term. |
| sub_var/2 | Generates
(on backtracking) all subterms (==) of Term. |