Description: Theorem *14.205 in WhiteheadRussell p. 190. (Contributed by Andrew Salmon, 11-Jul-2011)
Ref | Expression | ||
---|---|---|---|
Assertion | iotasbc5 | |- ( E! x ph -> ( [. ( iota x ph ) / y ]. ps <-> E. y ( y = ( iota x ph ) /\ ps ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sbc5 | |- ( [. ( iota x ph ) / y ]. ps <-> E. y ( y = ( iota x ph ) /\ ps ) ) |
|
2 | 1 | a1i | |- ( E! x ph -> ( [. ( iota x ph ) / y ]. ps <-> E. y ( y = ( iota x ph ) /\ ps ) ) ) |