Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
The empty set
raaan
Next ⟩
raaanv
Metamath Proof Explorer
Ascii
Unicode
Theorem
raaan
Description:
Rearrange restricted quantifiers.
(Contributed by
NM
, 26-Oct-2010)
Ref
Expression
Hypotheses
raaan.1
⊢
Ⅎ
y
φ
raaan.2
⊢
Ⅎ
x
ψ
Assertion
raaan
⊢
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
Proof
Step
Hyp
Ref
Expression
1
raaan.1
⊢
Ⅎ
y
φ
2
raaan.2
⊢
Ⅎ
x
ψ
3
rzal
⊢
A
=
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
4
rzal
⊢
A
=
∅
→
∀
x
∈
A
φ
5
rzal
⊢
A
=
∅
→
∀
y
∈
A
ψ
6
pm5.1
⊢
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
∧
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
7
3
4
5
6
syl12anc
⊢
A
=
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
8
1
r19.28z
⊢
A
≠
∅
→
∀
y
∈
A
φ
∧
ψ
↔
φ
∧
∀
y
∈
A
ψ
9
8
ralbidv
⊢
A
≠
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
10
nfcv
⊢
Ⅎ
_
x
A
11
10
2
nfralw
⊢
Ⅎ
x
∀
y
∈
A
ψ
12
11
r19.27z
⊢
A
≠
∅
→
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
13
9
12
bitrd
⊢
A
≠
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
14
7
13
pm2.61ine
⊢
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ