Since learning and reasoning tasks are often expressed in English with simple, direct counterparts
in the classical rst-order logic language (FOL), it is necessary for FLARE to
translate FOL clauses into their AVL equivalent. AVL is clearly not as expressive as FOL,
so that FLARE has some inherent limitations. For the purposes of this discussion, let predicates
of the form p(x) and p(x; C) where C is a constant be called avl-predicates. Then,
the FOL clauses that can be translated into AVL are of two kinds: