Description: The base set of a topological space. (Contributed by FL, 27-Jun-2014)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | istps.a | |- A = ( Base ` K ) |
|
| istps.j | |- J = ( TopOpen ` K ) |
||
| Assertion | tpsuni | |- ( K e. TopSp -> A = U. J ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | istps.a | |- A = ( Base ` K ) |
|
| 2 | istps.j | |- J = ( TopOpen ` K ) |
|
| 3 | 1 2 | istps2 | |- ( K e. TopSp <-> ( J e. Top /\ A = U. J ) ) |
| 4 | 3 | simprbi | |- ( K e. TopSp -> A = U. J ) |