Theorem bj-exalbial 36235

Description: Adding a second quantifier over the same variable is a transparent operation, (∃∀ case). (Contributed by BJ, 20-Oct-2019.)

Assertion

Ref	Expression
bj-exalbial	⊢ (∃𝑥∀𝑥𝜑 ↔ ∀𝑥𝜑)

Proof of Theorem bj-exalbial

Step	Hyp	Ref	Expression
1		nfa1 2140	. 2 ⊢ Ⅎ𝑥∀𝑥𝜑
2	1	19.9 2193	1 ⊢ (∃𝑥∀𝑥𝜑 ↔ ∀𝑥𝜑)

Syntax hints:   ↔ wb 205  ∀wal 1531  ∃wex 1773

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-10 2129  ax-12 2166

This theorem depends on definitions:  df-bi 206  df-or 846  df-ex 1774  df-nf 1778

This theorem is referenced by: (None)