<s>
In	O
model	B-Application
checking	I-Application
,	O
a	O
subfield	O
of	O
computer	B-General_Concept
science	I-General_Concept
,	O
a	O
signal	O
or	O
timed	B-Application
state	I-Application
sequence	I-Application
is	O
an	O
extension	O
of	O
the	O
notion	O
of	O
words	O
,	O
in	O
a	O
formal	O
language	O
,	O
in	O
which	O
letters	O
are	O
continuously	O
emitted	O
.	O
</s>
<s>
This	O
allow	O
to	O
use	O
formalism	O
similar	O
to	O
the	O
ones	O
of	O
automata	B-Application
theory	I-Application
to	O
deal	O
with	O
continuous	O
signal	O
.	O
</s>
<s>
A	O
statement	O
such	O
as	O
this	O
one	O
is	O
usually	O
expressed	O
in	O
metric	B-Application
temporal	I-Application
logic	I-Application
,	O
an	O
extension	O
of	O
linear	O
temporal	O
logic	O
which	O
allow	O
to	O
express	O
time	O
constraints	O
.	O
</s>
<s>
A	O
signal	O
may	O
be	O
passed	O
to	O
a	O
model	O
,	O
such	O
as	O
a	O
signal	B-Application
automaton	I-Application
,	O
which	O
will	O
decide	O
,	O
given	O
the	O
letters	O
or	O
actions	O
which	O
already	O
occurred	O
,	O
what	O
is	O
the	O
next	O
action	O
which	O
should	O
be	O
done	O
.	O
</s>
<s>
Having	O
the	O
finite	O
variability	O
property	O
is	O
similar	O
to	O
the	O
notion	O
of	O
being	O
non-Zeno	O
for	O
a	O
timed	B-Application
word	I-Application
.	O
</s>
<s>
Assume	O
we	O
need	O
to	O
create	O
a	O
system	O
,	O
such	O
as	O
a	O
signal	B-Application
automaton	I-Application
,	O
which	O
need	O
to	O
recall	O
everything	O
which	O
occurred	O
in	O
the	O
last	O
time	O
units	O
.	O
</s>
<s>
A	O
signal	B-Application
automaton	I-Application
reading	O
a	O
bipartite	O
signal	O
has	O
a	O
special	O
form	O
.	O
</s>
