Geography Reference
In-Depth Information
Fig. A.3.
Venn diagram/Euler circles
A
∪
B
: the union
A
∪
B
of two sets
A
and
B
is the set of all elements
which are in the set
Aor
the set
B
:
A
∪
B
:=
{
x
|
x
∈
A
∨
x
∈
B
}
Fig. A.4.
Venn diagram/Euler circles: the symmetric difference
AΔB
of two sets
A
and
B
is the set of all
elements which are
either
in set
Aor
in set
B
:
AΔB
:=
A
˙
{
x
|
x
∈
∨
x
∈
B
}
Fig. A.5.
Venn diagram/Euler circles: the difference set
A
\
B
of two sets
A
and
B
is the set of all elements of
A
which are
not
in
B
:
A
\
B
:=
{
x
|
x
∈
A
∧
x
∈
B
}
M
2
=
{
1
},M
3
=
{
2
},M
4
=
{
3
},
M
5
=
{
1
,
2
}
,M
6
=
{
2
,
3
}
,M
7
=
{
3
,
1
}
,
(A.8)
,
namely built on eight elements:
power(
M
)=
M
8
=
{
1
,
2
.
3
}
{∅
,
{
1
}
,
{
2
}
,
{
3
}
,
{
12
}
,
{
13
}
,
{
23
}
,
{
123
}}
.
(A.9)
End of Example.
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