Theorem negantlem8 856

Description: Negated antecedent identity. (Contributed by NM, 6-Aug-2001.)

Hypothesis

Ref	Expression
negant.1	(a →1 c) = (b →1 c)

Assertion

Ref	Expression
negantlem8	(a⊥ ∪ c) = (b⊥ ∪ c)

Proof of Theorem negantlem8

Step	Hyp	Ref	Expression
1		negant.1	. . . 4 (a →1 c) = (b →1 c)
2	1	negantlem6 854	. . 3 (a ∩ c⊥ ) = (b ∩ c⊥ )
3	2	ax-r4 37	. 2 (a ∩ c⊥ )⊥ = (b ∩ c⊥ )⊥
4		oran2 92	. 2 (a⊥ ∪ c) = (a ∩ c⊥ )⊥
5		oran2 92	. 2 (b⊥ ∪ c) = (b ∩ c⊥ )⊥
6	3, 4, 5	3tr1 63	1 (a⊥ ∪ c) = (b⊥ ∪ c)

This proof depends on syntax axioms:   = wb 1  ^⊥ wn 4   ∪ wo 6   ∩ wa 7   →₁ wi1 12

This proof depends on 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 proof depends on definitions:  df-b 39  df-a 40  df-t 41  df-f 42  df-i1 44  df-le1 130  df-le2 131  df-c1 132  df-c2 133

This theorem is used by:  negantlem9  859  negantlem10  861