Theorem wa4 194

Description: Weak A4. (Contributed by NM, 27-Sep-1997.)

Assertion

Ref	Expression
wa4	((a ∪ (b ∪ b⊥ )) ≡ (b ∪ b⊥ )) = 1

Proof of Theorem wa4

Step	Hyp	Ref	Expression
1		ax-a4 33	. 2 (a ∪ (b ∪ b⊥ )) = (b ∪ b⊥ )
2	1	bi1 118	1 ((a ∪ (b ∪ b⊥ )) ≡ (b ∪ b⊥ )) = 1

Syntax hints:   = wb 1  ^⊥ wn 4   ≡ tb 5   ∪ wo 6  1wt 8

This theorem was proved from axioms:  ax-a1 30  ax-a2 31  ax-a4 33  ax-a5 34  ax-r1 35  ax-r2 36  ax-r4 37  ax-r5 38

This theorem depends on definitions:  df-b 39  df-a 40  df-t 41  df-f 42

This theorem is referenced by:  wdid0id5  1111  wdid0id1  1112  wdid0id2  1113  wdid0id3  1114  wdid0id4  1115