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Description: The group operation for the singleton group. Obsolete, use grp1 . instead. (Contributed by NM, 4-Nov-2006) (New usage is discouraged.) (Proof modification is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | grposnOLD.1 | |- A e. _V |
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| Assertion | grposnOLD | |- { <. <. A , A >. , A >. } e. GrpOp |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | grposnOLD.1 | |- A e. _V |
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| 2 | snex | |- { A } e. _V |
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| 3 | opex | |- <. A , A >. e. _V |
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| 4 | 3 1 | f1osn | |- { <. <. A , A >. , A >. } : { <. A , A >. } -1-1-onto-> { A } |
| 5 | f1of | |- ( { <. <. A , A >. , A >. } : { <. A , A >. } -1-1-onto-> { A } -> { <. <. A , A >. , A >. } : { <. A , A >. } --> { A } ) |
|
| 6 | 4 5 | ax-mp | |- { <. <. A , A >. , A >. } : { <. A , A >. } --> { A } |
| 7 | 1 1 | xpsn | |- ( { A } X. { A } ) = { <. A , A >. } |
| 8 | 7 | feq2i | |- ( { <. <. A , A >. , A >. } : ( { A } X. { A } ) --> { A } <-> { <. <. A , A >. , A >. } : { <. A , A >. } --> { A } ) |
| 9 | 6 8 | mpbir | |- { <. <. A , A >. , A >. } : ( { A } X. { A } ) --> { A } |
| 10 | velsn | |- ( x e. { A } <-> x = A ) |
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| 11 | velsn | |- ( y e. { A } <-> y = A ) |
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| 12 | velsn | |- ( z e. { A } <-> z = A ) |
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| 13 | oveq2 | |- ( z = A -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } z ) = ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } A ) ) |
|
| 14 | oveq1 | |- ( x = A -> ( x { <. <. A , A >. , A >. } y ) = ( A { <. <. A , A >. , A >. } y ) ) |
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| 15 | oveq2 | |- ( y = A -> ( A { <. <. A , A >. , A >. } y ) = ( A { <. <. A , A >. , A >. } A ) ) |
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| 16 | df-ov | |- ( A { <. <. A , A >. , A >. } A ) = ( { <. <. A , A >. , A >. } ` <. A , A >. ) |
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| 17 | 3 1 | fvsn | |- ( { <. <. A , A >. , A >. } ` <. A , A >. ) = A |
| 18 | 16 17 | eqtri | |- ( A { <. <. A , A >. , A >. } A ) = A |
| 19 | 15 18 | eqtrdi | |- ( y = A -> ( A { <. <. A , A >. , A >. } y ) = A ) |
| 20 | 14 19 | sylan9eq | |- ( ( x = A /\ y = A ) -> ( x { <. <. A , A >. , A >. } y ) = A ) |
| 21 | 20 | oveq1d | |- ( ( x = A /\ y = A ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } A ) = ( A { <. <. A , A >. , A >. } A ) ) |
| 22 | 21 18 | eqtrdi | |- ( ( x = A /\ y = A ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } A ) = A ) |
| 23 | 13 22 | sylan9eqr | |- ( ( ( x = A /\ y = A ) /\ z = A ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } z ) = A ) |
| 24 | 23 | 3impa | |- ( ( x = A /\ y = A /\ z = A ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } z ) = A ) |
| 25 | oveq1 | |- ( x = A -> ( x { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) = ( A { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) ) |
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| 26 | oveq1 | |- ( y = A -> ( y { <. <. A , A >. , A >. } z ) = ( A { <. <. A , A >. , A >. } z ) ) |
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| 27 | oveq2 | |- ( z = A -> ( A { <. <. A , A >. , A >. } z ) = ( A { <. <. A , A >. , A >. } A ) ) |
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| 28 | 27 18 | eqtrdi | |- ( z = A -> ( A { <. <. A , A >. , A >. } z ) = A ) |
| 29 | 26 28 | sylan9eq | |- ( ( y = A /\ z = A ) -> ( y { <. <. A , A >. , A >. } z ) = A ) |
| 30 | 29 | oveq2d | |- ( ( y = A /\ z = A ) -> ( A { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) = ( A { <. <. A , A >. , A >. } A ) ) |
| 31 | 30 18 | eqtrdi | |- ( ( y = A /\ z = A ) -> ( A { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) = A ) |
| 32 | 25 31 | sylan9eq | |- ( ( x = A /\ ( y = A /\ z = A ) ) -> ( x { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) = A ) |
| 33 | 32 | 3impb | |- ( ( x = A /\ y = A /\ z = A ) -> ( x { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) = A ) |
| 34 | 24 33 | eqtr4d | |- ( ( x = A /\ y = A /\ z = A ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } z ) = ( x { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) ) |
| 35 | 10 11 12 34 | syl3anb | |- ( ( x e. { A } /\ y e. { A } /\ z e. { A } ) -> ( ( x { <. <. A , A >. , A >. } y ) { <. <. A , A >. , A >. } z ) = ( x { <. <. A , A >. , A >. } ( y { <. <. A , A >. , A >. } z ) ) ) |
| 36 | 1 | snid | |- A e. { A } |
| 37 | oveq2 | |- ( x = A -> ( A { <. <. A , A >. , A >. } x ) = ( A { <. <. A , A >. , A >. } A ) ) |
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| 38 | 37 18 | eqtrdi | |- ( x = A -> ( A { <. <. A , A >. , A >. } x ) = A ) |
| 39 | id | |- ( x = A -> x = A ) |
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| 40 | 38 39 | eqtr4d | |- ( x = A -> ( A { <. <. A , A >. , A >. } x ) = x ) |
| 41 | 10 40 | sylbi | |- ( x e. { A } -> ( A { <. <. A , A >. , A >. } x ) = x ) |
| 42 | 36 | a1i | |- ( x e. { A } -> A e. { A } ) |
| 43 | 10 38 | sylbi | |- ( x e. { A } -> ( A { <. <. A , A >. , A >. } x ) = A ) |
| 44 | 2 9 35 36 41 42 43 | isgrpoi | |- { <. <. A , A >. , A >. } e. GrpOp |