<s>
In	O
the	O
computer	B-General_Concept
science	I-General_Concept
fields	O
of	O
knowledge	O
engineering	O
and	O
ontology	O
,	O
the	O
Sigma	B-Application
knowledge	I-Application
engineering	I-Application
environment	I-Application
is	O
an	O
open	B-License
source	I-License
computer	O
program	O
for	O
the	O
development	O
of	O
formal	O
ontologies	O
.	O
</s>
<s>
It	O
is	O
designed	O
for	O
use	O
with	O
the	O
Suggested	B-Language
Upper	I-Language
Merged	I-Language
Ontology	I-Language
.	O
</s>
<s>
It	O
originally	O
included	O
only	O
the	O
Vampire	O
theorem	O
prover	O
as	O
its	O
core	O
deductive	O
inference	O
engine	O
,	O
but	O
now	O
allows	O
use	O
of	O
many	O
other	O
provers	O
that	O
have	O
participated	O
in	O
the	O
CASC/CADE	O
competitions	O
.	O
</s>
