Theorem dneg-P1.13b 72

Description: Double Negation Law B.

The other related law is dneg-P1.13a 71.

Assertion

Ref	Expression
dneg-P1.13b	⊢ (𝜑 → ¬ ¬ 𝜑)

Proof of Theorem dneg-P1.13b

Step	Hyp	Ref	Expression
1		dneg-P1.13a 71	. 2 ⊢ (¬ ¬ ¬ 𝜑 → ¬ 𝜑)
2	1	axL3.SH 32	1 ⊢ (𝜑 → ¬ ¬ 𝜑)

Syntax hints:  ¬ wff-neg 9   → wff-imp 10

This theorem was proved from axioms:  ax-L1 11  ax-L2 12  ax-L3 13  ax-MP 14

This theorem is referenced by:  trnsp-P1.15b  78  trnsp-P1.15c  80