Theorem or1r 105

Description: Disjunction with 1. (Contributed by NM, 26-Nov-1997.)

Assertion

Ref	Expression
or1r	(1 ∪ a) = 1

Proof of Theorem or1r

Step	Hyp	Ref	Expression
1		ax-a2 31	. 2 (1 ∪ a) = (a ∪ 1)
2		or1 104	. 2 (a ∪ 1) = 1
3	1, 2	ax-r2 36	1 (1 ∪ a) = 1

Syntax hints:   = wb 1   ∪ wo 6  1wt 8

This theorem was proved from axioms:  ax-a2 31  ax-a4 33  ax-r1 35  ax-r2 36  ax-r5 38

This theorem depends on definitions:  df-t 41

This theorem is referenced by:  ud3lem1c  568  ud3lem3  576  ud5lem1  589  i1orni1  847  lem3.3.7i1e1  1060  lem3.3.7i1e2  1061  lem3.3.7i2e1  1063  lem3.3.7i2e2  1064