Theorem u2lemc1 663

Description: Commutation theorem for Dishkant implication.

Assertion

Ref	Expression
u2lemc1	b C (a ->2 b)

Proof of Theorem u2lemc1

Step	Hyp	Ref	Expression
1		comid 179	. . 3 b C b
2		comanr2 447	. . . 4 b_|_ C (a_|_ ^ b_|_)
3	2	comcom6 441	. . 3 b C (a_|_ ^ b_|_)
4	1, 3	com2or 465	. 2 b C (b v (a_|_ ^ b_|_))
5		df-i2 44	. . 3 (a ->2 b) = (b v (a_|_ ^ b_|_))
6	5	ax-r1 34	. 2 (b v (a_|_ ^ b_|_)) = (a ->2 b)
7	4, 6	cbtr 174	1 b C (a ->2 b)

Syntax hints:   C wc 3  _|_wn 4   v wo 6   ^ wa 7   ->2 wi2 14

This theorem is referenced by:  u2lemc3 674  u21lembi 709  u2lem3 732  imp3 823  oa23 916

This theorem was proved from axioms:  ax-a1 29  ax-a2 30  ax-a3 31  ax-a4 32  ax-a5 33  ax-r1 34  ax-r2 35  ax-r4 36  ax-r5 37  ax-r3 421

This theorem depends on definitions:  df-b 38  df-a 39  df-t 40  df-f 41  df-i2 44  df-le1 122  df-le2 123  df-c1 124  df-c2 125

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