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Metamath Proof Explorer

Theorem neg1z

Description: -1 is an integer. (Contributed by David A. Wheeler, 5-Dec-2018)

		Ref	Expression
	Assertion	neg1z	$⊢ - 1 \in ℤ$

Step	Hyp	Ref	Expression
1		1nn	$⊢ 1 \in ℕ$
2		nnnegz	$⊢ 1 \in ℕ \to - 1 \in ℤ$
3	1 2	ax-mp	$⊢ - 1 \in ℤ$