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˃ |
min
(μ, ˃) |
| μ |
μ r
r
,
(μ, ˃) |= i = 1 min
with
|
min
(μ(
x i ), ˃(
x i ))
.
In last example, it is
|
min
(μ, ˃) |=
0
.
7
+
0
.
7
+
1
+
0
.
6
=
3
, | μ |=
0
.
7
+
0
.
8
+
1
+
0
.
7
=
3
.
2, and r
=
3
/
3
.
2
=
0
.
9375
0
.
94. That is,
μ
9375 ˃ : μ
'is almost
0
.
included in'
˃
.
|
min
(μ,˃) |
| ˃ |
Since
| ˃ |=
0
.
70001
+
0
.
7
+
1
+
0
.
6
=
3
.
00001, it is
=
0
.
9999, or
˃ 0 . 9999 μ
. That is,
˃
is more included in
μ
, than
μ
is included in
˃
!
Remark 2.2.2 Of course, if
μ ˃
,itismin
(μ, ˃) = μ
, and r
=
1, that is,
μ ˃ μ 1 ˃.
Nevertheless, since it is only
min
(μ(
x i ), ˃(
x i ))
min
(
μ(
x i ),
˃(
x i )),
from
μ 1 ˃
(or
|
min
(μ, ˃) | | μ |
) it does not necessarily follow
μ ˃
.
Let us show an example with crisp subsets. If X
={
1
,
2
,
3
,
4
,
5
,
6
,
7
}
, and A
=
{
1
,
3
,
5
,
7
}
, B
={
1
,
3
,
5
,
6
}
,itis
7
7
7
min
A (
i
), μ B (
i
)) =
3
,
1 μ B (
i
) =
4
,
1 μ A (
i
) =
4
.
i
=
1
i
=
i
=
hence
μ A
μ B ,
or A
B
3
4
3
4
μ B
μ A ,
or B
A
3
4
3
4
2.2.2 Algebras of Fuzzy Sets
X
Once F
(
X
) = ( [
0
,
1
]
; ;= )
is taken, a general algebra of fuzzy sets comes from
endowing F
(
X
)
with three operations:
X
X ,
1.
:[
0
,
1
]
ₒ[
0
,
1
]
X
X
X
2.
·:[
0
,
1
]
×[
0
,
1
]
ₒ[
0
,
1
]
,
X
X
X
3.
+:[
0
,
1
]
×[
0
,
1
]
ₒ[
0
,
1
]
,
μ of
respectively called the complement
μ
,the intersection
μ · ˃
of '
μ
and
˃
', and
X
; ;=; ·;+; )
the union
μ + ˃
of '
μ
or
˃
'. Then
( [
0
,
1
]
, is called an algebra of
fuzzy sets , provided the following laws do hold:
 
 
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