Description: Symmetry of equinumerosity. Deduction form of ensym . (Contributed by David Moews, 1-May-2017)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | ensymd.1 | |- ( ph -> A ~~ B ) |
|
| Assertion | ensymd | |- ( ph -> B ~~ A ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ensymd.1 | |- ( ph -> A ~~ B ) |
|
| 2 | ensym | |- ( A ~~ B -> B ~~ A ) |
|
| 3 | 1 2 | syl | |- ( ph -> B ~~ A ) |