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Set theory
Set theory: elementary operations relative to a universe
bj-rcleq
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bj-reabeq
Metamath Proof Explorer
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Unicode
Theorem
bj-rcleq
Description:
Relative version of
dfcleq
.
(Contributed by
BJ
, 27-Dec-2023)
Ref
Expression
Assertion
bj-rcleq
⊢
V
∩
A
=
V
∩
B
↔
∀
x
∈
V
x
∈
A
↔
x
∈
B
Proof
Step
Hyp
Ref
Expression
1
nfcv
⊢
Ⅎ
_
x
A
2
nfcv
⊢
Ⅎ
_
x
B
3
nfcv
⊢
Ⅎ
_
x
V
4
1
2
3
bj-rcleqf
⊢
V
∩
A
=
V
∩
B
↔
∀
x
∈
V
x
∈
A
↔
x
∈
B