Description: Obsolete version of sbievw as of 24-Aug-2025. (Contributed by NM, 30-Jun-1994) (Revised by BJ, 18-Jul-2023) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | sbievw.is | |- ( x = y -> ( ph <-> ps ) ) |
|
| Assertion | sbievwOLD | |- ( [ y / x ] ph <-> ps ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sbievw.is | |- ( x = y -> ( ph <-> ps ) ) |
|
| 2 | sb6 | |- ( [ y / x ] ph <-> A. x ( x = y -> ph ) ) |
|
| 3 | 1 | equsalvw | |- ( A. x ( x = y -> ph ) <-> ps ) |
| 4 | 2 3 | bitri | |- ( [ y / x ] ph <-> ps ) |