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Description: The element of the disjoint elements class and the disjoint elementhood predicate are the same, that is ( A e. ElDisjs <-> ElDisj A ) when A is a set. (Contributed by Peter Mazsa, 23-Jul-2023)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | eleldisjseldisj | |- ( A e. V -> ( A e. ElDisjs <-> ElDisj A ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eleldisjs | |- ( A e. V -> ( A e. ElDisjs <-> ( `' _E |` A ) e. Disjs ) ) |
|
| 2 | cnvepresex | |- ( A e. V -> ( `' _E |` A ) e. _V ) |
|
| 3 | eldisjsdisj | |- ( ( `' _E |` A ) e. _V -> ( ( `' _E |` A ) e. Disjs <-> Disj ( `' _E |` A ) ) ) |
|
| 4 | 2 3 | syl | |- ( A e. V -> ( ( `' _E |` A ) e. Disjs <-> Disj ( `' _E |` A ) ) ) |
| 5 | 1 4 | bitrd | |- ( A e. V -> ( A e. ElDisjs <-> Disj ( `' _E |` A ) ) ) |
| 6 | df-eldisj | |- ( ElDisj A <-> Disj ( `' _E |` A ) ) |
|
| 7 | 5 6 | bitr4di | |- ( A e. V -> ( A e. ElDisjs <-> ElDisj A ) ) |