  In the last two decades, modal and description logics have been applied to
numerous areas of computer science, including knowledge representation, formal
verification, database theory, distributed computing and, more recently,
semantic web and ontologies. For this reason, the problem of automated
reasoning in modal and description logics has been thoroughly investigated. In
particular, many approaches have been proposed for efficiently handling the
satisfiability of the core normal modal logic K(m), and of its notational
variant, the description logic ALC. Although simple in structure, K(m)/ALC is
computationally very hard to reason on, its satisfiability being
PSPACE-complete.
  In this paper we start exploring the idea of performing automated reasoning
tasks in modal and description logics by encoding them into SAT, so that to be
handled by state-of-the-art SAT tools; as with most previous approaches, we
begin our investigation from the satisfiability in K(m). We propose an
efficient encoding, and we test it on an extensive set of benchmarks, comparing
the approach with the main state-of-the-art tools available. Although the
encoding is necessarily worst-case exponential, from our experiments we notice
that, in practice, this approach can handle most or all the problems which are
at the reach of the other approaches, with performances which are comparable
with, or even better than, those of the current state-of-the-art tools.
