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Description: Meets in a topology are realized by intersections. (Contributed by Zhi Wang, 30-Sep-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | toplatmeet.i | |- I = ( toInc ` J ) |
|
| toplatmeet.j | |- ( ph -> J e. Top ) |
||
| toplatmeet.a | |- ( ph -> A e. J ) |
||
| toplatmeet.b | |- ( ph -> B e. J ) |
||
| toplatmeet.m | |- ./\ = ( meet ` I ) |
||
| Assertion | toplatmeet | |- ( ph -> ( A ./\ B ) = ( A i^i B ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | toplatmeet.i | |- I = ( toInc ` J ) |
|
| 2 | toplatmeet.j | |- ( ph -> J e. Top ) |
|
| 3 | toplatmeet.a | |- ( ph -> A e. J ) |
|
| 4 | toplatmeet.b | |- ( ph -> B e. J ) |
|
| 5 | toplatmeet.m | |- ./\ = ( meet ` I ) |
|
| 6 | eqid | |- ( glb ` I ) = ( glb ` I ) |
|
| 7 | 1 | ipopos | |- I e. Poset |
| 8 | 7 | a1i | |- ( ph -> I e. Poset ) |
| 9 | 6 5 8 3 4 | meetval | |- ( ph -> ( A ./\ B ) = ( ( glb ` I ) ` { A , B } ) ) |
| 10 | 3 4 | prssd | |- ( ph -> { A , B } C_ J ) |
| 11 | 6 | a1i | |- ( ph -> ( glb ` I ) = ( glb ` I ) ) |
| 12 | intprg | |- ( ( A e. J /\ B e. J ) -> |^| { A , B } = ( A i^i B ) ) |
|
| 13 | 3 4 12 | syl2anc | |- ( ph -> |^| { A , B } = ( A i^i B ) ) |
| 14 | inopn | |- ( ( J e. Top /\ A e. J /\ B e. J ) -> ( A i^i B ) e. J ) |
|
| 15 | 2 3 4 14 | syl3anc | |- ( ph -> ( A i^i B ) e. J ) |
| 16 | 13 15 | eqeltrd | |- ( ph -> |^| { A , B } e. J ) |
| 17 | unimax | |- ( |^| { A , B } e. J -> U. { x e. J | x C_ |^| { A , B } } = |^| { A , B } ) |
|
| 18 | 16 17 | syl | |- ( ph -> U. { x e. J | x C_ |^| { A , B } } = |^| { A , B } ) |
| 19 | 18 13 | eqtr2d | |- ( ph -> ( A i^i B ) = U. { x e. J | x C_ |^| { A , B } } ) |
| 20 | 1 2 10 11 19 15 | ipoglb | |- ( ph -> ( ( glb ` I ) ` { A , B } ) = ( A i^i B ) ) |
| 21 | 9 20 | eqtrd | |- ( ph -> ( A ./\ B ) = ( A i^i B ) ) |