axfrege31 - Mathbox for Richard Penner

	Mathbox for Richard Penner		< Previous Next > Nearby theorems
Mirrors > Home > MPE Home > Th. List > Mathboxes > axfrege31		Structured version Visualization version GIF version

Theorem axfrege31 44619

Description: Identical to notnotr 131. Axiom 31 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.)

**Assertion**
Ref	Expression
axfrege31	⊢ (¬ ¬ 𝜑 → 𝜑)

**Proof of Theorem axfrege31**
Step	Hyp	Ref	Expression
1		notnotr 131	1 ⊢ (¬ ¬ 𝜑 → 𝜑)

Colors of variables: wff setvar class

This proof depends on syntax axioms: ¬ wn 3 → wi 4

This proof depends on axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8

This theorem is used by: (None)