Description: Closed intervals are closed sets of II . Note that iccss , iccordt , and ordtresticc are proved from ixxss12 , ordtcld3 , and ordtrest2 , respectively. An alternate proof uses restcldi , dfii2 , and icccld . (Contributed by Zhi Wang, 8-Sep-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | icccldii | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | iccssxr | |
|
2 | iccordt | |
|
3 | 0re | |
|
4 | 1re | |
|
5 | iccss | |
|
6 | 3 4 5 | mpanl12 | |
7 | letopuni | |
|
8 | 7 | restcldi | |
9 | 1 2 6 8 | mp3an12i | |
10 | dfii5 | |
|
11 | ordtresticc | |
|
12 | 10 11 | eqtr4i | |
13 | 12 | fveq2i | |
14 | 9 13 | eleqtrrdi | |