Theorem 19.9rv 941

Description: Special case of Theorem 19.9 of [Margaris] p. 89.

Assertion

Ref	Expression
19.9rv	⊢ (φ ↔ ∃xφ)

Distinct variable group(s):   φ,x

Proof of Theorem 19.9rv

Step	Hyp	Ref	Expression
1		ax-17 925	. 2 ⊢ (φ → ∀xφ)
2	1	19.9r 718	1 ⊢ (φ ↔ ∃xφ)

Syntax hints:   ↔ wb 127  ∃wex 678

This theorem is referenced by:  zfcndext 3759  zfcndpow 3762

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-gen 677  ax-17 925

This theorem depends on definitions:  df-bi 128  df-ex 679

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