<s>
In	O
computer	B-General_Concept
science	I-General_Concept
and	O
artificial	B-Application
intelligence	I-Application
,	O
ontology	B-Language
languages	I-Language
are	O
formal	O
languages	O
used	O
to	O
construct	O
ontologies	B-Language
.	O
</s>
<s>
Ontology	B-Language
languages	I-Language
are	O
usually	O
declarative	B-Language
languages	I-Language
,	O
are	O
almost	O
always	O
generalizations	O
of	O
frame	O
languages	O
,	O
and	O
are	O
commonly	O
based	O
on	O
either	O
first-order	O
logic	O
or	O
on	O
description	B-Language
logic	I-Language
.	O
</s>
<s>
These	O
languages	O
use	O
a	O
markup	O
scheme	O
to	O
encode	O
knowledge	O
,	O
most	O
commonly	O
with	O
XML	B-Protocol
.	O
</s>
<s>
Description	B-Language
logic	I-Language
provides	O
an	O
extension	O
of	O
frame	O
languages	O
,	O
without	O
going	O
so	O
far	O
as	O
to	O
take	O
the	O
leap	O
to	O
first-order	O
logic	O
and	O
support	O
for	O
arbitrary	O
predicates	O
.	O
</s>
<s>
OWL	B-Language
.	O
</s>
<s>
Gellish	O
is	O
an	O
example	O
of	O
a	O
combined	O
ontology	B-Language
language	I-Language
and	O
ontology	B-Language
that	O
is	O
description	B-Language
logic	I-Language
based	O
.	O
</s>
<s>
Several	O
ontology	B-Language
languages	I-Language
support	O
expressions	O
in	O
first-order	O
logic	O
and	O
allow	O
general	O
predicates	O
.	O
</s>
