Definition df-n0 8876

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 8875	. 2 class NN0
2		cn 8624	. . 3 class NN
3		cc0 7541	. . . 4 class 0
4	3	csn 3491	. . 3 class { 0 }
5	2, 4	cun 3033	. 2 class ( NN u. { 0 } )
6	1, 5	wceq 1312	1 wff NN0 = ( NN u. { 0 } )

This definition is referenced by:  elnn0  8877  nnssnn0  8878  nn0ssre  8879  nn0ex  8881  dfn2  8888  nn0addcl  8910  nn0mulcl  8911  nn0ssz  8970