Definition df-9 9056

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 9048	. 2 class 9
2		c8 9047	. . 3 class 8
3		c1 7880	. . 3 class 1
4		caddc 7882	. . 3 class +
5	2, 3, 4	co 5922	. 2 class ( 8 + 1 )
6	1, 5	wceq 1364	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9077  9pos  9094  9m1e8  9116  8p1e9  9131  5p4e9  9139  6p3e9  9141  7p2e9  9142  9nn  9159  8lt9  9188  8p2e10  9536  9p9e18  9550  9t9e81  9585  lgsdir2lem5  15273  2lgsoddprmlem3d  15351