Description: Universal class equality in terms of empty difference. (Contributed by NM, 17-Sep-2003)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | vdif0 | ⊢ ( 𝐴 = V ↔ ( V ∖ 𝐴 ) = ∅ ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | vss | ⊢ ( V ⊆ 𝐴 ↔ 𝐴 = V ) | |
| 2 | ssdif0 | ⊢ ( V ⊆ 𝐴 ↔ ( V ∖ 𝐴 ) = ∅ ) | |
| 3 | 1 2 | bitr3i | ⊢ ( 𝐴 = V ↔ ( V ∖ 𝐴 ) = ∅ ) |