  Every definite logic program has as its meaning a least Herbrand model with
respect to the program-independent ordering "set-inclusion". In the case of
normal logic programs there do not exist least models in general. However,
according to a recent approach by Rondogiannis and Wadge, who consider
infinite-valued models, every normal logic program does have a least model with
respect to a program-independent ordering. We show that this approach can be
extended to formula-based logic programs (i.e., finite sets of rules of the
form A\leftarrowF where A is an atom and F an arbitrary first-order formula).
We construct for a given program P an interpretation M_P and show that it is
the least of all models of P. Keywords: Logic programming, semantics of
programs, negation-as-failure, infinite-valued logics, set theory
