Description: Bound-variable hypothesis builder for the iota class. (Contributed by Andrew Salmon, 11-Jul-2011) (Revised by Mario Carneiro, 15-Oct-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | nfiota1 | |- F/_ x ( iota x ph ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfiota2 | |- ( iota x ph ) = U. { y | A. x ( ph <-> x = y ) } |
|
2 | nfaba1 | |- F/_ x { y | A. x ( ph <-> x = y ) } |
|
3 | 2 | nfuni | |- F/_ x U. { y | A. x ( ph <-> x = y ) } |
4 | 1 3 | nfcxfr | |- F/_ x ( iota x ph ) |