Definition df-9 8882

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 8874	. 2 class 9
2		c8 8873	. . 3 class 8
3		c1 7716	. . 3 class 1
4		caddc 7718	. . 3 class +
5	2, 3, 4	co 5818	. 2 class ( 8 + 1 )
6	1, 5	wceq 1335	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  8903  9pos  8920  9m1e8  8942  8p1e9  8956  5p4e9  8964  6p3e9  8966  7p2e9  8967  9nn  8984  8lt9  9013  8p2e10  9357  9p9e18  9371  9t9e81  9406