Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Richard Penner
Natural addition of Cantor normal forms
rp-abid
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Metamath Proof Explorer
Ascii
Unicode
Theorem
rp-abid
Description:
Two ways to express a class.
(Contributed by
RP
, 13-Feb-2025)
Ref
Expression
Assertion
rp-abid
⊢
A
=
x
|
∃
a
∈
A
x
=
a
Proof
Step
Hyp
Ref
Expression
1
clel5
⊢
x
∈
A
↔
∃
a
∈
A
x
=
a
2
1
eqabi
⊢
A
=
x
|
∃
a
∈
A
x
=
a