Theorem wl-pm2.21 33259

Description: From a wff and its negation, anything follows. Theorem *2.21 of [WhiteheadRussell] p. 104. Also called the Duns Scotus law. Copy of pm2.21 120 with a different proof. (Contributed by Wolf Lammen, 17-Dec-2018.) (New usage is discouraged.) (Proof modification is discouraged.)

Assertion

Ref	Expression
wl-pm2.21	|- ( -. ph -> ( ph -> ps ) )

Proof of Theorem wl-pm2.21

Step	Hyp	Ref	Expression
1		ax-luk3 33243	. 2 |- ( ph -> ( -. ph -> ps ) )
2	1	wl-com12 33258	1 |- ( -. ph -> ( ph -> ps ) )

Syntax hints:   -. wn 3   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-luk1 33241  ax-luk2 33242  ax-luk3 33243

This theorem is referenced by:  wl-con1i  33260  wl-ax2  33264