Availability:built-in
chk postfix was 
considered to refer to determinism as in e.g., memberchk/2. 
This predicate respects constraints.
See section 5.6 for defining clauses whose head is unified using single sided unification.
chk postfix was 
considered to refer to determinism as in e.g., memberchk/2. 
This predicate respects constraints.
See section 5.6 for defining clauses whose head is unified using single sided unification.