| Description: Alternate proof of pw0 4763.
The proofs have a similar structure: pw0 4763
uses the definitions of powerclass and singleton as class abstractions,
whereas bj-pw0ALT 37033 uses characterizations of their elements.
Both proofs
then use transitivity of a congruence relation (equality for pw0 4763
and
biconditional for bj-pw0ALT 37033) to translate the property ss0b 4352
into the
wanted result. To translate a biconditional into a class equality, pw0 4763
uses abbii 2796 (which yields an equality of class
abstractions), while
bj-pw0ALT 37033 uses eqriv 2726 (which requires a biconditional of membership
of
a given setvar variable). Note that abbii 2796, through its closed form
abbi 2794, is proved from eqrdv 2727, which is the deduction form of eqriv 2726.
In the other direction, velpw 4556 and velsn 4593 are proved from the
definitions of powerclass and singleton using elabg 3632, which is a version
of abbii 2796 suited for membership characterizations.
(Contributed by BJ,
14-Apr-2024.) (Proof modification is discouraged.)
(New usage is discouraged.) |
