Theorem nnzOLD

Description: Obsolete version of nnz as of 1-Feb-2025. (Contributed by NM, 9-May-2004) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	nnzOLD	|- ( N e. NN -> N e. ZZ )

Proof

Step	Hyp	Ref	Expression
1		nnssz	|- NN C_ ZZ
2	1	sseli	|- ( N e. NN -> N e. ZZ )