| 21. | Note that infinite intersections of open sets need not be open.
|
| 22. | The open sets are just the upper sets with respect to d ".
|
| 23. | "It was a very warm and open set, " she says.
|
| 24. | The open set between two level curves of " V " is connected.
|
| 25. | Open sets in \ mathbb { S } are unions of such rectangles.
|
| 26. | In metrizable spaces, every open set is an F ? set.
|
| 27. | As is the case with interval ( or open set ).
|
| 28. | The indicator function of any open set is lower semicontinuous.
|
| 29. | Note that all poles are exterior to the open set.
|
| 30. | The above definition is useful if the notion of open set is already defined.
|
