Description: Adding a second quantifier is a tranparent operation, ( E. E. case). (Contributed by BJ, 20-Oct-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | bj-exexbiex | ⊢ ( ∃ 𝑥 ∃ 𝑥 𝜑 ↔ ∃ 𝑥 𝜑 ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nfe1 | ⊢ Ⅎ 𝑥 ∃ 𝑥 𝜑 | |
2 | 1 | 19.9 | ⊢ ( ∃ 𝑥 ∃ 𝑥 𝜑 ↔ ∃ 𝑥 𝜑 ) |