Description: A symmetry with E. .
See negsym1 for more information. (Contributed by Anthony Hart, 4-Sep-2011)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | exisym1 | ⊢ ( ∃ 𝑥 ∃ 𝑥 ⊥ → ∃ 𝑥 𝜑 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfe1 | ⊢ Ⅎ 𝑥 ∃ 𝑥 𝜑 | |
| 2 | falim | ⊢ ( ⊥ → 𝜑 ) | |
| 3 | 2 | eximi | ⊢ ( ∃ 𝑥 ⊥ → ∃ 𝑥 𝜑 ) |
| 4 | 1 3 | exlimi | ⊢ ( ∃ 𝑥 ∃ 𝑥 ⊥ → ∃ 𝑥 𝜑 ) |