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Description: Joins in a dual order are meets in the original. (Contributed by Stefan O'Rear, 29-Jan-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | oduglb.d | |- D = ( ODual ` O ) |
|
| odujoin.m | |- ./\ = ( meet ` O ) |
||
| Assertion | odujoin | |- ./\ = ( join ` D ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | oduglb.d | |- D = ( ODual ` O ) |
|
| 2 | odujoin.m | |- ./\ = ( meet ` O ) |
|
| 3 | eqid | |- ( glb ` O ) = ( glb ` O ) |
|
| 4 | 1 3 | odulub | |- ( O e. _V -> ( glb ` O ) = ( lub ` D ) ) |
| 5 | 4 | breqd | |- ( O e. _V -> ( { a , b } ( glb ` O ) c <-> { a , b } ( lub ` D ) c ) ) |
| 6 | 5 | oprabbidv | |- ( O e. _V -> { <. <. a , b >. , c >. | { a , b } ( glb ` O ) c } = { <. <. a , b >. , c >. | { a , b } ( lub ` D ) c } ) |
| 7 | eqid | |- ( meet ` O ) = ( meet ` O ) |
|
| 8 | 3 7 | meetfval | |- ( O e. _V -> ( meet ` O ) = { <. <. a , b >. , c >. | { a , b } ( glb ` O ) c } ) |
| 9 | 1 | fvexi | |- D e. _V |
| 10 | eqid | |- ( lub ` D ) = ( lub ` D ) |
|
| 11 | eqid | |- ( join ` D ) = ( join ` D ) |
|
| 12 | 10 11 | joinfval | |- ( D e. _V -> ( join ` D ) = { <. <. a , b >. , c >. | { a , b } ( lub ` D ) c } ) |
| 13 | 9 12 | mp1i | |- ( O e. _V -> ( join ` D ) = { <. <. a , b >. , c >. | { a , b } ( lub ` D ) c } ) |
| 14 | 6 8 13 | 3eqtr4d | |- ( O e. _V -> ( meet ` O ) = ( join ` D ) ) |
| 15 | fvprc | |- ( -. O e. _V -> ( meet ` O ) = (/) ) |
|
| 16 | fvprc | |- ( -. O e. _V -> ( ODual ` O ) = (/) ) |
|
| 17 | 1 16 | eqtrid | |- ( -. O e. _V -> D = (/) ) |
| 18 | 17 | fveq2d | |- ( -. O e. _V -> ( join ` D ) = ( join ` (/) ) ) |
| 19 | join0 | |- ( join ` (/) ) = (/) |
|
| 20 | 18 19 | eqtrdi | |- ( -. O e. _V -> ( join ` D ) = (/) ) |
| 21 | 15 20 | eqtr4d | |- ( -. O e. _V -> ( meet ` O ) = ( join ` D ) ) |
| 22 | 14 21 | pm2.61i | |- ( meet ` O ) = ( join ` D ) |
| 23 | 2 22 | eqtri | |- ./\ = ( join ` D ) |