Theorem oal1 980

Description: Orthoarguesian law - →₁ version derived from →₁ version.

Assertion

Ref	Expression
oal1	((a →1 c) ∩ ((a ∩ b) ∪ ((a →1 c) ∩ (b →1 c)))) ≤ (b →1 c)

Proof of Theorem oal1

Step	Hyp	Ref	Expression
1		oal2 979	. 2 ((c⊥ →2 a⊥ ) ∩ ((a⊥ ∪ b⊥ )⊥ ∪ ((c⊥ →2 a⊥ ) ∩ (c⊥ →2 b⊥ )))) ≤ (c⊥ →2 b⊥ )
2		i1i2 258	. . 3 (a →1 c) = (c⊥ →2 a⊥ )
3		df-a 39	. . . 4 (a ∩ b) = (a⊥ ∪ b⊥ )⊥
4		i1i2 258	. . . . 5 (b →1 c) = (c⊥ →2 b⊥ )
5	2, 4	2an 72	. . . 4 ((a →1 c) ∩ (b →1 c)) = ((c⊥ →2 a⊥ ) ∩ (c⊥ →2 b⊥ ))
6	3, 5	2or 67	. . 3 ((a ∩ b) ∪ ((a →1 c) ∩ (b →1 c))) = ((a⊥ ∪ b⊥ )⊥ ∪ ((c⊥ →2 a⊥ ) ∩ (c⊥ →2 b⊥ )))
7	2, 6	2an 72	. 2 ((a →1 c) ∩ ((a ∩ b) ∪ ((a →1 c) ∩ (b →1 c)))) = ((c⊥ →2 a⊥ ) ∩ ((a⊥ ∪ b⊥ )⊥ ∪ ((c⊥ →2 a⊥ ) ∩ (c⊥ →2 b⊥ ))))
8	1, 7, 4	le3tr1 132	1 ((a →1 c) ∩ ((a ∩ b) ∪ ((a →1 c) ∩ (b →1 c)))) ≤ (b →1 c)

Syntax hints:   ≤ wle 2  ^⊥ wn 4   ∪ wo 6   ∩ wa 7   →₁ wi1 13   →₂ wi2 14

This theorem was proved from axioms:  ax-a1 29  ax-a2 30  ax-a5 33  ax-r1 34  ax-r2 35  ax-r4 36  ax-r5 37  ax-3oa 978

This theorem depends on definitions:  df-a 39  df-i1 43  df-i2 44  df-le1 122  df-le2 123

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