Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | bnj937.1 | |- ( ph -> E. x ps ) |
|
| Assertion | bnj937 | |- ( ph -> ps ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | bnj937.1 | |- ( ph -> E. x ps ) |
|
| 2 | 19.9v | |- ( E. x ps <-> ps ) |
|
| 3 | 1 2 | sylib | |- ( ph -> ps ) |