Theorem u3lem4 758

Description: Lemma for unified implication study. (Contributed by NM, 21-Jan-1998.)

Assertion

Ref	Expression
u3lem4	(a →3 (a →3 (b →3 a))) = 1

Proof of Theorem u3lem4

Step	Hyp	Ref	Expression
1		lem4 511	. 2 (a →3 (a →3 (b →3 a))) = (a⊥ ∪ (b →3 a))
2		ax-a2 31	. . 3 (a⊥ ∪ (b →3 a)) = ((b →3 a) ∪ a⊥ )
3		u3lemonb 637	. . 3 ((b →3 a) ∪ a⊥ ) = 1
4	2, 3	ax-r2 36	. 2 (a⊥ ∪ (b →3 a)) = 1
5	1, 4	ax-r2 36	1 (a →3 (a →3 (b →3 a))) = 1

Syntax hints:   = wb 1  ^⊥ wn 4   ∪ wo 6  1wt 8   →₃ wi3 14

This theorem was proved from axioms:  ax-a1 30  ax-a2 31  ax-a3 32  ax-a4 33  ax-a5 34  ax-r1 35  ax-r2 36  ax-r4 37  ax-r5 38  ax-r3 439

This theorem depends on definitions:  df-b 39  df-a 40  df-t 41  df-f 42  df-i3 46  df-le1 130  df-le2 131  df-c1 132  df-c2 133

This theorem is referenced by: (None)