<s>
The	O
term	O
“	O
adaptation	O
”	O
in	O
computer	B-General_Concept
science	I-General_Concept
refers	O
to	O
a	O
process	O
where	O
an	O
interactive	B-General_Concept
system	I-General_Concept
(	O
adaptive	O
system	O
)	O
adapts	O
its	O
behaviour	O
to	O
individual	O
users	O
based	O
on	O
information	O
acquired	O
about	O
its	O
user(s )	O
and	O
its	O
environment	O
.	O
</s>
<s>
A	O
software	O
system	O
passes	O
through	O
a	O
potentially	O
long	O
software	B-General_Concept
engineering	I-General_Concept
cycle	O
and	O
before	O
delivery	O
,	O
requirement	O
engineers	O
,	O
designers	O
and	O
software	B-Application
developers	I-Application
realize	O
the	O
components	O
of	O
the	O
system	O
.	O
</s>
<s>
The	O
active	O
involvement	O
of	O
users	O
and	O
clear	O
understanding	O
of	O
user	O
and	O
task	B-General_Concept
requirements	O
is	O
a	O
challenge	O
in	O
the	O
development	O
of	O
computer-based	O
interactive	B-General_Concept
systems	O
for	O
two	O
reasons	O
:	O
</s>
<s>
With	O
their	O
norm	O
for	O
"	O
Human-centred	O
design	O
processes	O
for	O
interactive	B-General_Concept
systems	O
"	O
the	O
International	O
Organization	O
for	O
Standardization	O
gives	O
guidance	O
on	O
user-centered	O
design	O
activities	O
throughout	O
the	O
life	O
cycle	O
of	O
computer-based	O
interactive	B-General_Concept
systems	O
.	O
</s>
<s>
One	O
of	O
the	O
core	O
tasks	O
of	O
user-centred	O
design	O
is	O
to	O
negotiate	O
and	O
facilitate	O
the	O
communication	O
across	O
the	O
well-known	O
user-developer	O
gap	O
while	O
acknowledging	O
the	O
different	O
forms	O
of	O
expression	O
and	O
different	O
requirements	O
on	O
each	O
side	O
.	O
</s>
<s>
Here	O
again	O
it	O
is	O
impossible	O
for	O
developers	B-Application
to	O
anticipate	O
all	O
possible	O
requirements	O
modifications	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
developers	B-Application
implement	O
techniques	O
of	O
adaptation	O
into	O
the	O
system	O
in	O
order	O
to	O
react	O
to	O
changing	O
conditions	O
as	O
fast	O
as	O
possible	O
.	O
</s>
<s>
The	O
consideration	O
of	O
user	O
preferences	O
like	O
language	O
,	O
colour	O
schemes	O
,	O
modality	B-General_Concept
of	O
interaction	O
,	O
menu	O
options	O
or	O
security	O
properties	O
,	O
and	O
numberless	O
other	O
personal	O
preferences	O
are	O
popular	O
sources	O
of	O
adaptation	O
and	O
can	O
be	O
reused	O
in	O
different	O
applications	O
.	O
</s>
<s>
Intra-individual	O
differences	O
consider	O
the	O
evolution	O
and	O
further	O
development	O
of	O
a	O
single	O
user	O
,	O
as	O
well	O
as	O
the	O
task	B-General_Concept
over	O
time	O
.	O
</s>
<s>
In	O
the	O
same	O
manner	O
,	O
the	O
need	O
for	O
a	O
higher	O
flexibility	B-Application
of	O
computer	O
systems	O
is	O
pushed	O
by	O
the	O
changing	O
of	O
the	O
tasks	O
to	O
be	O
accomplished	O
with	O
such	O
a	O
system	O
.	O
</s>
<s>
Unlike	O
desktop	B-Device
applications	I-Device
,	O
which	O
rely	O
on	O
a	O
carefully	O
configured	O
and	O
largely	O
static	O
set	O
of	O
resources	O
,	O
ubiquitous	B-Architecture
computing	I-Architecture
applications	O
are	O
subject	O
to	O
changes	O
in	O
available	O
resources	O
such	O
as	O
network	O
connectivity	O
and	O
input/output	O
devices	O
.	O
</s>
