Theorem 1nn0

Description: 1 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002)

	Ref	Expression
Assertion	1nn0	⊢ 1 ∈ ℕ0

Proof

Step	Hyp	Ref	Expression
1		1nn	⊢ 1 ∈ ℕ
2	1	nnnn0i	⊢ 1 ∈ ℕ0