Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Power Sets
Functions
fmptapd
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fmptpr
Metamath Proof Explorer
Ascii
Unicode
Theorem
fmptapd
Description:
Append an additional value to a function.
(Contributed by
Thierry Arnoux
, 3-Jan-2017)
Ref
Expression
Hypotheses
fmptapd.0a
⊢
φ
→
A
∈
V
fmptapd.0b
⊢
φ
→
B
∈
V
fmptapd.1
⊢
φ
→
R
∪
A
=
S
fmptapd.2
⊢
φ
∧
x
=
A
→
C
=
B
Assertion
fmptapd
⊢
φ
→
x
∈
R
⟼
C
∪
A
B
=
x
∈
S
⟼
C
Proof
Step
Hyp
Ref
Expression
1
fmptapd.0a
⊢
φ
→
A
∈
V
2
fmptapd.0b
⊢
φ
→
B
∈
V
3
fmptapd.1
⊢
φ
→
R
∪
A
=
S
4
fmptapd.2
⊢
φ
∧
x
=
A
→
C
=
B
5
4
1
2
fmptsnd
⊢
φ
→
A
B
=
x
∈
A
⟼
C
6
5
uneq2d
⊢
φ
→
x
∈
R
⟼
C
∪
A
B
=
x
∈
R
⟼
C
∪
x
∈
A
⟼
C
7
mptun
⊢
x
∈
R
∪
A
⟼
C
=
x
∈
R
⟼
C
∪
x
∈
A
⟼
C
8
7
a1i
⊢
φ
→
x
∈
R
∪
A
⟼
C
=
x
∈
R
⟼
C
∪
x
∈
A
⟼
C
9
3
mpteq1d
⊢
φ
→
x
∈
R
∪
A
⟼
C
=
x
∈
S
⟼
C
10
6
8
9
3eqtr2d
⊢
φ
→
x
∈
R
⟼
C
∪
A
B
=
x
∈
S
⟼
C