Metamath Proof Explorer


Theorem icccldii

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 0AB1ABClsdII

Proof

Step Hyp Ref Expression
1 iccssxr 01*
2 iccordt ABClsdordTop
3 0re 0
4 1re 1
5 iccss 010AB1AB01
6 3 4 5 mpanl12 0AB1AB01
7 letopuni *=ordTop
8 7 restcldi 01*ABClsdordTopAB01ABClsdordTop𝑡01
9 1 2 6 8 mp3an12i 0AB1ABClsdordTop𝑡01
10 dfii5 II=ordTop01×01
11 ordtresticc ordTop𝑡01=ordTop01×01
12 10 11 eqtr4i II=ordTop𝑡01
13 12 fveq2i ClsdII=ClsdordTop𝑡01
14 9 13 eleqtrrdi 0AB1ABClsdII