  Space and time are basic categories of any top-level ontology. They are
fundamental assumptions for the mode of existence of those individuals which
are said to be in space and time. In the present paper the ontology of space in
the General Formal Ontology (GFO) is expounded. This ontology is represented as
a theory BT (Brentano Theory), which is specified by a set of axioms formalized
in first-order logic. This theory uses four primitive relations: SReg(x) (x is
space region), spart(x, y) (x is spatial part of y), sb(x, y) (x is spatial
boundary of y), and scoinc(x, y) (x and y spatially coincide). This ontology is
inspired by ideas of Franz Brentano. The investigation and exploration of Franz
Brentano's ideas on space and time began about twenty years ago by work of R.M.
Chisholm, B. Smith and A. Varzi. The present paper takes up this line of
research and makes a further step in establishing an ontology of space which is
based on rigorous logical methods and on principles of the new philosophical
approach of integrative realism.
