  In this note, we use Kunen's notion of a signing to establish two theorems
about the well-founded semantics of logic programs, in the case where we are
interested in only (say) the positive literals of a predicate $p$ that are
consequences of the program. The first theorem identifies a class of programs
for which the well-founded and Fitting semantics coincide for the positive part
of $p$. The second theorem shows that if a program has a signing then computing
the positive part of $p$ under the well-founded semantics requires the
computation of only one part of each predicate. This theorem suggests an
analysis for query-answering under the well-founded semantics. In the process
of proving these results, we use an alternative formulation of the well-founded
semantics of logic programs, which might be of independent interest.
  Under consideration in Theory and Practice of Logic Programming (TPLP)
