Theorem 4nn0

Description: 4 is a nonnegative integer. (Contributed by Mario Carneiro, 18-Feb-2014)

	Ref	Expression
Assertion	4nn0	$$⊢4\in {\mathbb{N}}_0$$

Proof

Step	Hyp	Ref	Expression
1		4nn	$$⊢4\in \mathbb{N}$$
2	1	nnnn0i	$$⊢4\in {\mathbb{N}}_0$$