<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
an	O
attributed	B-Application
graph	I-Application
grammar	I-Application
is	O
a	O
class	O
of	O
graph	B-Application
grammar	I-Application
that	O
associates	O
vertices	O
with	O
a	O
set	O
of	O
attributes	O
and	O
rewrites	O
with	O
functions	O
on	O
attributes	O
.	O
</s>
<s>
In	O
the	O
algebraic	O
approach	O
to	O
graph	B-Application
grammars	I-Application
,	O
they	O
are	O
usually	O
formulated	O
using	O
the	O
double-pushout	B-Application
approach	I-Application
or	O
the	O
single-pushout	B-Application
approach	I-Application
.	O
</s>
<s>
AGG	O
,	O
a	O
rule-based	O
visual	O
language	O
that	O
directly	O
expresses	O
attributed	B-Application
graph	I-Application
grammars	I-Application
using	O
the	O
single-pushout	B-Application
approach	I-Application
has	O
been	O
developed	O
at	O
TU	O
Berlin	O
for	O
many	O
years	O
.	O
</s>
