Theorem u2lemnonb 676

Description: Lemma for Dishkant implication study.

Assertion

Ref	Expression
u2lemnonb	((a ->2 b)' v b') = b'

Proof of Theorem u2lemnonb

Step	Hyp	Ref	Expression
1		df-a 40	. . . 4 ((a ->2 b) ^ b) = ((a ->2 b)' v b')'
2	1	ax-r1 35	. . 3 ((a ->2 b)' v b')' = ((a ->2 b) ^ b)
3		u2lemab 611	. . 3 ((a ->2 b) ^ b) = b
4	2, 3	ax-r2 36	. 2 ((a ->2 b)' v b')' = b
5	4	con3 68	1 ((a ->2 b)' v b') = b'

Syntax hints:   = wb 1  'wn 4   v wo 6   ^ wa 7   ->2 wi2 13

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

This theorem depends on definitions:  df-a 40  df-i2 45

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