  The importance of taking individual, potentially conflicting perspectives
into account when dealing with knowledge has been widely recognised. Many
existing ontology management approaches fully merge knowledge perspectives,
which may require weakening in order to maintain consistency; others represent
the distinct views in an entirely detached way.
  As an alternative, we propose Standpoint Logic, a simple, yet versatile
multi-modal logic "add-on" for existing KR languages intended for the
integrated representation of domain knowledge relative to diverse, possibly
conflicting standpoints, which can be hierarchically organised, combined and
put in relation to each other.
  Starting from the generic framework of First-Order Standpoint Logic (FOSL),
we subsequently focus our attention on the fragment of sentential formulas, for
which we provide a polytime translation into the standpoint-free version. This
result yields decidability and favourable complexities for a variety of highly
expressive decidable fragments of first-order logic. Using some elaborate
encoding tricks, we then establish a similar translation for the very
expressive description logic SROIQb_s underlying the OWL 2 DL ontology
language. By virtue of this result, existing highly optimised OWL reasoners can
be used to provide practical reasoning support for ontology languages extended
by standpoint modelling.
