Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
The empty set
raaanv
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sbss
Metamath Proof Explorer
Ascii
Unicode
Theorem
raaanv
Description:
Rearrange restricted quantifiers.
(Contributed by
NM
, 11-Mar-1997)
Ref
Expression
Assertion
raaanv
⊢
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
Proof
Step
Hyp
Ref
Expression
1
rzal
⊢
A
=
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
2
rzal
⊢
A
=
∅
→
∀
x
∈
A
φ
3
rzal
⊢
A
=
∅
→
∀
y
∈
A
ψ
4
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
5
1
2
3
4
syl12anc
⊢
A
=
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
6
r19.28zv
⊢
A
≠
∅
→
∀
y
∈
A
φ
∧
ψ
↔
φ
∧
∀
y
∈
A
ψ
7
6
ralbidv
⊢
A
≠
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
8
r19.27zv
⊢
A
≠
∅
→
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
9
7
8
bitrd
⊢
A
≠
∅
→
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ
10
5
9
pm2.61ine
⊢
∀
x
∈
A
∀
y
∈
A
φ
∧
ψ
↔
∀
x
∈
A
φ
∧
∀
y
∈
A
ψ