Description: Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of Megill p. 448 (p. 16 of preprint). (Contributed by NM, 27-Feb-2005)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | drsb2 | |- ( A. x x = y -> ( [ x / z ] ph <-> [ y / z ] ph ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sbequ | |- ( x = y -> ( [ x / z ] ph <-> [ y / z ] ph ) ) |
|
| 2 | 1 | sps | |- ( A. x x = y -> ( [ x / z ] ph <-> [ y / z ] ph ) ) |