<s>
In	O
automata	B-Application
theory	I-Application
,	O
a	O
co-Büchi	B-General_Concept
automaton	I-General_Concept
is	O
a	O
variant	O
of	O
Büchi	B-General_Concept
automaton	I-General_Concept
.	O
</s>
<s>
The	O
only	O
difference	O
is	O
the	O
accepting	O
condition	O
:	O
a	O
Co-Büchi	B-General_Concept
automaton	I-General_Concept
accepts	O
an	O
infinite	O
word	O
if	O
there	O
exists	O
a	O
run	O
,	O
such	O
that	O
all	O
the	O
states	O
occurring	O
infinitely	O
often	O
in	O
the	O
run	O
are	O
in	O
the	O
final	O
state	O
set	O
.	O
</s>
<s>
In	O
contrast	O
,	O
a	O
Büchi	B-General_Concept
automaton	I-General_Concept
accepts	O
a	O
word	O
if	O
there	O
exists	O
a	O
run	O
,	O
such	O
that	O
at	O
least	O
one	O
state	O
occurring	O
infinitely	O
often	O
in	O
the	O
final	O
state	O
set	O
.	O
</s>
<s>
(	O
Deterministic	O
)	O
Co-Büchi	O
automata	O
are	O
strictly	O
weaker	O
than	O
(	O
nondeterministic	O
)	O
Büchi	B-General_Concept
automata	I-General_Concept
.	O
</s>
<s>
Formally	O
,	O
a	O
deterministic	O
co-Büchi	B-General_Concept
automaton	I-General_Concept
is	O
a	O
tuple	O
that	O
consists	O
of	O
the	O
following	O
components	O
:	O
</s>
<s>
In	O
a	O
non-deterministic	O
co-Büchi	B-General_Concept
automaton	I-General_Concept
,	O
the	O
transition	O
function	O
is	O
replaced	O
with	O
a	O
transition	O
relation	O
.	O
</s>
<s>
Generally	O
,	O
the	O
term	O
co-Büchi	B-General_Concept
automaton	I-General_Concept
refers	O
to	O
the	O
non-deterministic	O
co-Büchi	B-General_Concept
automaton	I-General_Concept
.	O
</s>
<s>
For	O
more	O
comprehensive	O
formalism	O
see	O
also	O
ω-automaton	B-General_Concept
.	O
</s>
