Theorem nn0ssq

Description: The nonnegative integers are a subset of the rationals. (Contributed by NM, 31-Jul-2004)

	Ref	Expression
Assertion	nn0ssq	⊢ ℕ0 ⊆ ℚ

Proof

Step	Hyp	Ref	Expression
1		nn0ssz	⊢ ℕ0 ⊆ ℤ
2		zssq	⊢ ℤ ⊆ ℚ
3	1 2	sstri	⊢ ℕ0 ⊆ ℚ