Definition df-n0 8978

Description: Define the set of nonnegative integers. (Contributed by Raph Levien, 10-Dec-2002.)

Assertion

Ref	Expression
df-n0	|- NN0 = ( NN u. { 0 } )

Detailed syntax breakdown of Definition df-n0

Step	Hyp	Ref	Expression
1		cn0 8977	. 2 class NN0
2		cn 8720	. . 3 class NN
3		cc0 7620	. . . 4 class 0
4	3	csn 3527	. . 3 class { 0 }
5	2, 4	cun 3069	. 2 class ( NN u. { 0 } )
6	1, 5	wceq 1331	1 wff NN0 = ( NN u. { 0 } )

This definition is referenced by:  elnn0  8979  nnssnn0  8980  nn0ssre  8981  nn0ex  8983  dfn2  8990  nn0addcl  9012  nn0mulcl  9013  nn0ssz  9072