Theorem u5lemc4 687

Description: Lemma for relevance implication study.

Hypothesis

Ref	Expression
ulemc3.1	a C b

Assertion

Ref	Expression
u5lemc4	(a ->5 b) = (a_|_ v b)

Proof of Theorem u5lemc4

Step	Hyp	Ref	Expression
1		df-i5 47	. 2 (a ->5 b) = (((a ^ b) v (a_|_ ^ b)) v (a_|_ ^ b_|_))
2		ulemc3.1	. . . . . . 7 a C b
3		comid 179	. . . . . . . 8 a C a
4	3	comcom2 175	. . . . . . 7 a C a_|_
5	2, 4	fh2r 456	. . . . . 6 ((a v a_|_) ^ b) = ((a ^ b) v (a_|_ ^ b))
6	5	ax-r1 34	. . . . 5 ((a ^ b) v (a_|_ ^ b)) = ((a v a_|_) ^ b)
7		ancom 68	. . . . . 6 ((a v a_|_) ^ b) = (b ^ (a v a_|_))
8		df-t 40	. . . . . . . . 9 1 = (a v a_|_)
9	8	ax-r1 34	. . . . . . . 8 (a v a_|_) = 1
10	9	lan 70	. . . . . . 7 (b ^ (a v a_|_)) = (b ^ 1)
11		an1 98	. . . . . . 7 (b ^ 1) = b
12	10, 11	ax-r2 35	. . . . . 6 (b ^ (a v a_|_)) = b
13	7, 12	ax-r2 35	. . . . 5 ((a v a_|_) ^ b) = b
14	6, 13	ax-r2 35	. . . 4 ((a ^ b) v (a_|_ ^ b)) = b
15	14	ax-r5 37	. . 3 (((a ^ b) v (a_|_ ^ b)) v (a_|_ ^ b_|_)) = (b v (a_|_ ^ b_|_))
16	2	comcom3 436	. . . . 5 a_|_ C b
17	2	comcom4 437	. . . . 5 a_|_ C b_|_
18	16, 17	fh4 454	. . . 4 (b v (a_|_ ^ b_|_)) = ((b v a_|_) ^ (b v b_|_))
19		ax-a2 30	. . . . . 6 (b v a_|_) = (a_|_ v b)
20		df-t 40	. . . . . . 7 1 = (b v b_|_)
21	20	ax-r1 34	. . . . . 6 (b v b_|_) = 1
22	19, 21	2an 72	. . . . 5 ((b v a_|_) ^ (b v b_|_)) = ((a_|_ v b) ^ 1)
23		an1 98	. . . . 5 ((a_|_ v b) ^ 1) = (a_|_ v b)
24	22, 23	ax-r2 35	. . . 4 ((b v a_|_) ^ (b v b_|_)) = (a_|_ v b)
25	18, 24	ax-r2 35	. . 3 (b v (a_|_ ^ b_|_)) = (a_|_ v b)
26	15, 25	ax-r2 35	. 2 (((a ^ b) v (a_|_ ^ b)) v (a_|_ ^ b_|_)) = (a_|_ v b)
27	1, 26	ax-r2 35	1 (a ->5 b) = (a_|_ v b)

Syntax hints:   = wb 1   C wc 3  _|_wn 4   v wo 6   ^ wa 7  1wt 9   ->5 wi5 17

This theorem is referenced by:  u5lemle1 696  u5lem1 720  u5lem2 730  u5lem3 735  u5lem4 742

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-i5 47  df-le1 122  df-le2 123  df-c1 124  df-c2 125

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