Description: Equality of a class variable and a class abstraction. In this version, the fact that x is a nonfree variable in A is explicitly stated as a hypothesis. (Contributed by Thierry Arnoux, 11-May-2017) Avoid ax-13 . (Revised by Wolf Lammen, 13-May-2023)
Ref | Expression | ||
---|---|---|---|
Hypothesis | abeq2f.0 | |
|
Assertion | abeq2f | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | abeq2f.0 | |
|
2 | nfab1 | |
|
3 | 1 2 | cleqf | |
4 | abid | |
|
5 | 4 | bibi2i | |
6 | 5 | albii | |
7 | 3 6 | bitri | |