Definition df-9 9268

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 9260	. 2 class 9
2		c8 9259	. . 3 class 8
3		c1 8093	. . 3 class 1
4		caddc 8095	. . 3 class +
5	2, 3, 4	co 6028	. 2 class ( 8 + 1 )
6	1, 5	wceq 1398	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9289  9pos  9306  9m1e8  9328  8p1e9  9343  5p4e9  9351  6p3e9  9353  7p2e9  9354  9nn  9371  8lt9  9400  8p2e10  9751  9p9e18  9765  9t9e81  9800  lgsdir2lem5  15851  2lgsoddprmlem3d  15929