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Metamath Proof Explorer

Theorem nnzd

Description: A positive integer is an integer. (Contributed by Mario Carneiro, 28-May-2016)

		Ref	Expression
	Hypothesis	nnzd.1	$⊢ φ \to A \in ℕ$
	Assertion	nnzd	$⊢ φ \to A \in ℤ$

Step	Hyp	Ref	Expression
1		nnzd.1	$⊢ φ \to A \in ℕ$
2	1	nnnn0d	$⊢ φ \to A \in ℕ_{0}$
3	2	nn0zd	$⊢ φ \to A \in ℤ$