Definition df-9 9352

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 9344	. 2 class 9
2		c8 9343	. . 3 class 8
3		c1 8173	. . 3 class 1
4		caddc 8175	. . 3 class +
5	2, 3, 4	co 6078	. 2 class ( 8 + 1 )
6	1, 5	wceq 1402	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9373  9pos  9390  9m1e8  9412  8p1e9  9427  5p4e9  9435  6p3e9  9437  7p2e9  9438  9nn  9455  8lt9  9484  8p2e10  9838  9p9e18  9852  9t9e81  9887  lgsdir2lem5  16068  2lgsoddprmlem3d  16146