| Step |
Hyp |
Ref |
Expression |
| 1 |
|
opprnzr.1 |
|- O = ( oppR ` R ) |
| 2 |
1
|
opprringb |
|- ( R e. Ring <-> O e. Ring ) |
| 3 |
2
|
anbi1i |
|- ( ( R e. Ring /\ ( 1r ` R ) =/= ( 0g ` R ) ) <-> ( O e. Ring /\ ( 1r ` R ) =/= ( 0g ` R ) ) ) |
| 4 |
|
eqid |
|- ( 1r ` R ) = ( 1r ` R ) |
| 5 |
|
eqid |
|- ( 0g ` R ) = ( 0g ` R ) |
| 6 |
4 5
|
isnzr |
|- ( R e. NzRing <-> ( R e. Ring /\ ( 1r ` R ) =/= ( 0g ` R ) ) ) |
| 7 |
1 4
|
oppr1 |
|- ( 1r ` R ) = ( 1r ` O ) |
| 8 |
1 5
|
oppr0 |
|- ( 0g ` R ) = ( 0g ` O ) |
| 9 |
7 8
|
isnzr |
|- ( O e. NzRing <-> ( O e. Ring /\ ( 1r ` R ) =/= ( 0g ` R ) ) ) |
| 10 |
3 6 9
|
3bitr4i |
|- ( R e. NzRing <-> O e. NzRing ) |