Description: Power classes are closed under union. (Contributed by AV, 27-Feb-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | pwuncl | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | unexg | |
|
2 | elpwi | |
|
3 | elpwi | |
|
4 | unss | |
|
5 | 4 | biimpi | |
6 | 2 3 5 | syl2an | |
7 | 1 6 | elpwd | |