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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 ∈ ℤ

Step	Hyp	Ref	Expression
1		1nn	⊢ 1 ∈ ℕ
2		nnnegz	⊢ ( 1 ∈ ℕ → - 1 ∈ ℤ )
3	1 2	ax-mp	⊢ - 1 ∈ ℤ