Definition df-pe 149

Description: "Of course" is the dual of "Why not".

Assertion

Ref	Expression
df-pe	⊦ (! 𝜑 ⧟ ~ ? ~ 𝜑)

Detailed syntax breakdown of Definition df-pe

Step	Hyp	Ref	Expression
1		wph	. . 3 wff 𝜑
2	1	wpe 148	. 2 wff ! 𝜑
3	1	wneg 3	. . . 4 wff ~ 𝜑
4	3	wne 48	. . 3 wff ? ~ 𝜑
5	4	wneg 3	. 2 wff ~ ? ~ 𝜑
6	2, 5	wlb 55	1 wff (! 𝜑 ⧟ ~ ? ~ 𝜑)

This definition is referenced by: (None)