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Description: In a unitary ring, a unit is not a zero divisor. (Contributed by AV, 7-Mar-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ringunitnzdiv.b | |- B = ( Base ` R ) |
|
| ringunitnzdiv.z | |- .0. = ( 0g ` R ) |
||
| ringunitnzdiv.t | |- .x. = ( .r ` R ) |
||
| ringunitnzdiv.r | |- ( ph -> R e. Ring ) |
||
| ringunitnzdiv.y | |- ( ph -> Y e. B ) |
||
| ringunitnzdiv.x | |- ( ph -> X e. ( Unit ` R ) ) |
||
| Assertion | ringunitnzdiv | |- ( ph -> ( ( X .x. Y ) = .0. <-> Y = .0. ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ringunitnzdiv.b | |- B = ( Base ` R ) |
|
| 2 | ringunitnzdiv.z | |- .0. = ( 0g ` R ) |
|
| 3 | ringunitnzdiv.t | |- .x. = ( .r ` R ) |
|
| 4 | ringunitnzdiv.r | |- ( ph -> R e. Ring ) |
|
| 5 | ringunitnzdiv.y | |- ( ph -> Y e. B ) |
|
| 6 | ringunitnzdiv.x | |- ( ph -> X e. ( Unit ` R ) ) |
|
| 7 | eqid | |- ( 1r ` R ) = ( 1r ` R ) |
|
| 8 | eqid | |- ( Unit ` R ) = ( Unit ` R ) |
|
| 9 | 1 8 | unitcl | |- ( X e. ( Unit ` R ) -> X e. B ) |
| 10 | 6 9 | syl | |- ( ph -> X e. B ) |
| 11 | eqid | |- ( invr ` R ) = ( invr ` R ) |
|
| 12 | 8 11 1 | ringinvcl | |- ( ( R e. Ring /\ X e. ( Unit ` R ) ) -> ( ( invr ` R ) ` X ) e. B ) |
| 13 | 4 6 12 | syl2anc | |- ( ph -> ( ( invr ` R ) ` X ) e. B ) |
| 14 | oveq1 | |- ( e = ( ( invr ` R ) ` X ) -> ( e .x. X ) = ( ( ( invr ` R ) ` X ) .x. X ) ) |
|
| 15 | 14 | eqeq1d | |- ( e = ( ( invr ` R ) ` X ) -> ( ( e .x. X ) = ( 1r ` R ) <-> ( ( ( invr ` R ) ` X ) .x. X ) = ( 1r ` R ) ) ) |
| 16 | 15 | adantl | |- ( ( ph /\ e = ( ( invr ` R ) ` X ) ) -> ( ( e .x. X ) = ( 1r ` R ) <-> ( ( ( invr ` R ) ` X ) .x. X ) = ( 1r ` R ) ) ) |
| 17 | 8 11 3 7 | unitlinv | |- ( ( R e. Ring /\ X e. ( Unit ` R ) ) -> ( ( ( invr ` R ) ` X ) .x. X ) = ( 1r ` R ) ) |
| 18 | 4 6 17 | syl2anc | |- ( ph -> ( ( ( invr ` R ) ` X ) .x. X ) = ( 1r ` R ) ) |
| 19 | 13 16 18 | rspcedvd | |- ( ph -> E. e e. B ( e .x. X ) = ( 1r ` R ) ) |
| 20 | 1 3 7 2 4 10 19 5 | ringinvnzdiv | |- ( ph -> ( ( X .x. Y ) = .0. <-> Y = .0. ) ) |