The “all solution” predicates recognize the following construct as
meaning “there exists an X such that P is true”, and
treats it as equivalent to P. The use of this explicit
existential quantifier outside the setof/3 and bagof/3
constructs is superfluous and discouraged. Thus, the following two
goals are equivalent:
X^P
P
The following construct is meaningful in the context of modules (see ref-mod), meaning “P is true in the context of the M module”:
M:P