Database
BASIC ALGEBRAIC STRUCTURES
The complex numbers as an algebraic extensible structure
Definition and basic properties
xrsex
Next ⟩
xrsbas
Metamath Proof Explorer
Ascii
Unicode
Theorem
xrsex
Description:
The extended real structure is a set.
(Contributed by
Mario Carneiro
, 21-Aug-2015)
Ref
Expression
Assertion
xrsex
⊢
ℝ
𝑠
*
∈
V
Proof
Step
Hyp
Ref
Expression
1
df-xrs
⊢
ℝ
𝑠
*
=
Base
ndx
ℝ
*
+
ndx
+
𝑒
⋅
ndx
⋅
𝑒
∪
TopSet
⁡
ndx
ordTop
⁡
≤
≤
ndx
≤
dist
⁡
ndx
x
∈
ℝ
*
,
y
∈
ℝ
*
⟼
if
x
≤
y
y
+
𝑒
−
x
x
+
𝑒
−
y
2
tpex
⊢
Base
ndx
ℝ
*
+
ndx
+
𝑒
⋅
ndx
⋅
𝑒
∈
V
3
tpex
⊢
TopSet
⁡
ndx
ordTop
⁡
≤
≤
ndx
≤
dist
⁡
ndx
x
∈
ℝ
*
,
y
∈
ℝ
*
⟼
if
x
≤
y
y
+
𝑒
−
x
x
+
𝑒
−
y
∈
V
4
2
3
unex
⊢
Base
ndx
ℝ
*
+
ndx
+
𝑒
⋅
ndx
⋅
𝑒
∪
TopSet
⁡
ndx
ordTop
⁡
≤
≤
ndx
≤
dist
⁡
ndx
x
∈
ℝ
*
,
y
∈
ℝ
*
⟼
if
x
≤
y
y
+
𝑒
−
x
x
+
𝑒
−
y
∈
V
5
1
4
eqeltri
⊢
ℝ
𝑠
*
∈
V