Theorem tt 60

Description: Justification of Definition df-t 41 of true (1). This shows that the definition is independent of the variable used to define it. (Contributed by NM, 9-Aug-1997.)

Assertion

Ref	Expression
tt	(a ∪ a⊥ ) = (b ∪ b⊥ )

Proof of Theorem tt

Step	Hyp	Ref	Expression
1		ax-a4 33	. . . 4 ((b ∪ b⊥ ) ∪ (a ∪ a⊥ )) = (a ∪ a⊥ )
2	1	ax-r1 35	. . 3 (a ∪ a⊥ ) = ((b ∪ b⊥ ) ∪ (a ∪ a⊥ ))
3		ax-a2 31	. . 3 ((b ∪ b⊥ ) ∪ (a ∪ a⊥ )) = ((a ∪ a⊥ ) ∪ (b ∪ b⊥ ))
4	2, 3	ax-r2 36	. 2 (a ∪ a⊥ ) = ((a ∪ a⊥ ) ∪ (b ∪ b⊥ ))
5		ax-a4 33	. 2 ((a ∪ a⊥ ) ∪ (b ∪ b⊥ )) = (b ∪ b⊥ )
6	4, 5	ax-r2 36	1 (a ∪ a⊥ ) = (b ∪ b⊥ )

This proof depends on syntax axioms:   = wb 1  ^⊥ wn 4   ∪ wo 6

This proof depends on axioms:  ax-a2 31  ax-a4 33  ax-r1 35  ax-r2 36

This theorem is used by: (None)