Theorem wa4 186

Description: Weak A4.

Assertion

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

Proof of Theorem wa4

Step	Hyp	Ref	Expression
1		ax-a4 32	. 2 (a ∪ (b ∪ b⊥ )) = (b ∪ b⊥ )
2	1	bi1 110	1 ((a ∪ (b ∪ b⊥ )) ≡ (b ∪ b⊥ )) = 1

Syntax hints:   = wb 1  ^⊥ wn 4   ≡ tb 5   ∪ wo 6  1wt 9

This theorem was proved from axioms:  ax-a1 29  ax-a2 30  ax-a4 32  ax-a5 33  ax-r1 34  ax-r2 35  ax-r4 36  ax-r5 37

This theorem depends on definitions:  df-b 38  df-a 39  df-t 40  df-f 41

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