Theorem 19.9OLD 1784

Description: Obsolete proof of 19.9 1783 as of 30-Dec-2017. (Contributed by FL, 24-Mar-2007.) (Revised by Mario Carneiro, 24-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
19.9.1	⊢ Ⅎxφ

Assertion

Ref	Expression
19.9OLD	⊢ (∃xφ ↔ φ)

Proof of Theorem 19.9OLD

Step	Hyp	Ref	Expression
1		19.9.1	. 2 ⊢ Ⅎxφ
2		19.9t 1779	. 2 ⊢ (Ⅎxφ → (∃xφ ↔ φ))
3	1, 2	ax-mp 5	1 ⊢ (∃xφ ↔ φ)

Syntax hints:   ↔ wb 176  ∃wex 1541  Ⅎwnf 1544

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-11 1746

This theorem depends on definitions:  df-bi 177  df-ex 1542  df-nf 1545

This theorem is referenced by: (None)