Definition df-9 8105

Description: Define the number 9. (Contributed by NM, 27-May-1999.)

Assertion

Ref	Expression
df-9	|- 9 = ( 8 + 1 )

Detailed syntax breakdown of Definition df-9

Step	Hyp	Ref	Expression
1		c9 8096	. 2 class 9
2		c8 8095	. . 3 class 8
3		c1 6982	. . 3 class 1
4		caddc 6984	. . 3 class +
5	2, 3, 4	co 5532	. 2 class ( 8 + 1 )
6	1, 5	wceq 1284	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  8126  9pos  8143  8p1e9  8172  5p4e9  8180  6p3e9  8182  7p2e9  8183  9nn  8200  8lt9  8229  8p2e10  8556  9p9e18  8570  9t9e81  8605