Description: A subset of a topology's underlying set is included in its closure. (Contributed by NM, 22-Feb-2007)
Ref | Expression | ||
---|---|---|---|
Hypothesis | clscld.1 | |
|
Assertion | sscls | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | clscld.1 | |
|
2 | ssintub | |
|
3 | 1 | clsval | |
4 | 2 3 | sseqtrrid | |