Definition df-n0 7958

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 7957	. 2 class NN0
2		cn 7695	. . 3 class NN
3		cc0 6711	. . . 4 class 0
4	3	csn 3367	. . 3 class { 0 }
5	2, 4	cun 2909	. 2 class ( NN u. { 0 })
6	1, 5	wceq 1242	1 wff NN0 = ( NN u. { 0 })

This definition is referenced by:  elnn0  7959  nnssnn0  7960  nn0ssre  7961  nn0ex  7963  dfn2  7970  nn0addcl  7993  nn0mulcl  7994  nn0ssz  8039