The origins of this monograph lie in my Ph.D. dissertation of 1987 at
the University of Pennsylvania, which was concerned with proof
procedures for the Horn clause subset of logic. The rise of logic
programming has made this an important area of study. All Prologs are
based on a variant of resolution, and inherit various properties related
to this proof method. This monograph studies the paradigm of logic
programming in the context of graph-based proof procedures which are
unrelated to resolution. The monograph is not a general introduction to
logic programming, although it is self-contained with respect to the
mathematics used. It should appeal to the computer scientist or
mathematician interested in the general area we now call computational
logic. A large part of the monograph is devoted to detailed proofs that
the methods we present are sound and complete, which in the context of
the logic programming, means that the operational and denotational
semantics agree.