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=
X
1
×
X
1
×···×
in further considerations the Cartesian product
X
X
n
(considered
as a n-tuple
x
i
of variables
x
j
describing characteristic features of the element
u
i
)
[69, 150, 151].
The concept of the Cartesian product may be applied not only to the set
U
but
also to the algorithm
Al
g
.
Itmeans that through the algorithm
Al
g
=
(
, wemay consider decomposition
of this algorithm, applying the concept of the Cartesian product to the algorithm
Al
g
,
or to the set of states of the algorithm
U
.
U
,
F
)
2.4.1 The Decomposition of an Algorithm Based
on the Cartesian Product Versus
Problem of Autonomy
Let us consider the Cartesian product
X
=
X
1
×
X
2
×···×
X
m
, where the set
X
is
associated with the set
U
. Considering the function
F
:
u
k
u
k
+
1
F
(
)
=
(2.9)
and using the notation
u
k
corresponds
x
k
u
k
+
1
corresponds
x
k
+
1
,
,
(2.10)
x
k
+
1
1
x
k
+
1
2
where
x
k
x
1
,
x
2
,...,
x
m
),
x
k
+
1
x
k
+
1
m
)
it is noticeable that the partial function
F
may be replaced with the function (also
partial)
f
=
(
=
(
,
,...,
X
whose domain is the set defined on the basis of characteristic
features. The function
f
is defined by
:
X
ₒ
x
1
,
x
2
,...,
x
m
)
=
(
x
k
+
1
1
x
k
+
1
2
x
k
+
1
m
u
k
u
k
+
1
f
(
,
,...,
)
⃔
F
(
)
=
.
(2.11)
In further considerations without the loss of generality we may limit the decompo-
sition of the set
U
into only to two sets
X
1
and
X
2
. The constraint to only two sets does
not limit further considerations and all of the significant problems may be further
successfully analyzed. The set
X
is the Cartesian product of two sets
X
X
2
.
This limitation may be treated as the result of grouping the elements of the Carte-
sian product:
X
=
X
1
×
=
X
1
×
X
2
, where
X
1
=
X
1
×
X
2
×···
X
i
,
X
2
=
X
i
+
1
×
X
i
+
2
×···
X
m
(Fig.
2.3
).
The projection of the set
X
onto the set
X
1 and
X
2 may be introduced by
Proj
1
:
X
1
×
X
2
ₒ
X
1
∀
(
x
1
,
x
2
)
∈
X
1
×
X
2
Proj
1
(
x
1
,
x
2
)
=
x
1
(2.12)
Proj
2
:
X
1
×
X
2
ₒ
X
2
∀
(
x
1
,
x
2
)
∈
X
1
×
X
2
Proj
2
(
x
1
,
x
2
)
=
x
2
The decomposition may now come down to the fact that it is necessary to form two
component algorithms
Al
g
1
and
Al
g
2
as in Fig.
2.4
. For this reason, it is necessary to